VCSEL light source with high temperature adaptability

Abstract

The invention relates to the technical field of semiconductor lasers, and discloses a high-temperature-adaptability VCSEL (Vertical Cavity Surface Emitting Laser) light source which comprises two VCSELs connected in parallel and can respectively obtain high-efficiency light output in low-temperature and high-temperature environments. Wherein the peak value of material gain of an active region of the VCSEL which normally works at low temperature at room temperature is located in the long wave direction of a resonant cavity mode; the peak value of the VCSEL material gain normally working at high temperature is located in the short wave direction of the cavity mode, so that the cavity mode moves towards the peak value of the material gain at low temperature and high temperature to obtain high mode gain. Two paths of lasers emitted by the VCSELs are combined into one path through the optical fiber beam combiner, so that the device can realize stable light output within a large temperature change range, and the temperature monitoring and prediction layer and the adaptive layer are arranged to realize temperature monitoring and prediction and intelligent adaptive adjustment.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor lasers and discloses a VCSEL light source with high temperature adaptability. Background Art

[0002] As a device for generating optical signals, semiconductor lasers play an irreplaceable role in optical fiber communication systems. According to the different light emission directions, semiconductor lasers can be divided into edge-emitting lasers (EEL) and surface-emitting lasers (VCSEL). Among them, surface-emitting lasers have gradually become the main light source for short-distance optical communication due to their advantages such as low cost, symmetrical light spot, high electro-optical conversion efficiency, easy arraying, and on-wafer testing. Unlike edge-emitting lasers, the laser wavelength emitted by surface-emitting lasers is determined by the DBR reflector structure on both sides of the laser and the material layer structure of the light-emitting area in the center. Since the thickness of its resonant cavity is only a few microns, the mode spacing of its longitudinal mode is large, so it is usually single-longitudinal mode lasing. As the temperature increases, the refractive index of the DBR material of the surface-emitting laser increases, resulting in an increase in its optical thickness, a red shift in the reflection spectrum, and an increase in the wavelength of the light. However, the red shift rate of the VCSEL spectrum with increasing temperature is less than 0.1nm / ℃, which is usually an order of magnitude lower than the red shift rate of the edge-emitting laser spectrum, so it has better wavelength stability.

[0003] In order to obtain high optical gain at room temperature, traditional surface-emitting lasers usually make the cavity mode of the device correspond to the peak value of the gain of the active region material to reduce the threshold of the device and improve the electro-optical conversion efficiency. However, as the temperature increases, the material gain decreases and its red shift speed is much faster than the cavity mode red shift speed, which causes the mode gain of conventional VCSELs to decrease rapidly in high temperature environments. Even after reaching a certain temperature, the optical power decreases instead of increasing with the increase of current, that is, thermal inversion of power occurs. This characteristic seriously affects the adaptability of VCSELs to high-temperature operation.

[0004] In order to improve the high-temperature working characteristics of VCSEL, the existing technology separates the cavity mode from the material gain peak of the active region at room temperature by wavelength detuning, so that the cavity mode and the material gain peak are close to each other when the temperature rises, thereby obtaining good high-temperature working performance. However, the mismatch degree of such devices in low-temperature environments is greater than that of conventional VCSELs, so their quantum efficiency decreases rapidly at low temperatures, and it is difficult to take into account stable operation over a large temperature range. However, automotive devices usually need to be able to withstand a wide range of temperature changes from -40°C to 85°C. Conventional VCSELs and single high-temperature working VCSELs are difficult to meet this requirement. Therefore, there is an urgent need for a VCSEL light source that can achieve stable output over a large temperature range from low to high temperatures.

[0005] For example, the existing patent with publication number CN110301076B discloses a light source array (1), comprising a plurality of VCSELs (2) arranged laterally to each other on a substrate (3), wherein each VCSEL (2) comprises a light emitting region (21) surrounded by an electrode structure (22) that does not emit light, wherein a shielding layer (4) is coated on at least the electrode structure (22), the shielding layer (4) only covers the surface (22s) of the electrode structure (22) facing the general light emitting direction (5) of the VECSEL (2), the shielding layer (4) is an opaque layer, and is adapted to optically match the array (10) in a closed state with the outer surface (11s) of the housing (11) of the device (10) in which the light source array (1) is to be installed. The present invention also describes a device (10) comprising such an array (1) and a method (100) for manufacturing the light source array (1).

[0006] The above patent lacks an active temperature control mechanism, making it difficult to cope with a wide temperature environment. It lacks an internal status monitoring function, making it difficult to know in advance whether abnormal temperature changes occur inside the light source. It cannot provide early warning and targeted optimization of factors that may affect the performance of the light source. The light intensity control lacks flexibility and has a relatively single functional focus. Summary of the invention

[0007] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0008] In order to solve the above technical problems, the main purpose of the present invention is to provide a high temperature adaptability VCSEL light source, comprising:

[0009] One end of the light beam combiner is connected to a metal electrode through an optical coupling optical fiber, and one end of the metal electrode is sequentially provided with a passivation layer, a P-type DBR reflector, an oxide layer, a multi-quantum well active region, an N-type DBR reflector, an N-type substrate layer, and a lower metal electrode;

[0010] One end of the light beam combiner is parallelly provided with a light coupling optical fiber connected to a phase matching layer;

[0011] The sensing layer monitors and predicts the temperature of the VCSEL light source by establishing a temperature model;

[0012] Adaptive layer, adaptively adjusts the intensity of VCSEL light source through temperature stratification.

[0013] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0014] The VCSEL light source comprises a low-temperature and a high-temperature vertical cavity surface emitting laser connected in parallel, wherein the low-temperature vertical cavity surface emitting laser and the high-temperature vertical cavity surface emitting laser are filled with BCB material;

[0015] The high-temperature vertical cavity surface emitting laser comprises:

[0016] One end of the passivation layer is connected to the metal electrode, and the other end is provided with a P-type DBR reflector;

[0017] An oxide layer is provided at the other end of the P-type DBR reflector, and the other end of the oxide layer is connected to the N-type DBR reflector through a multi-quantum well active region;

[0018] An N-type substrate layer is disposed at the other end of the N-type DBR reflector, and the N-type substrate layer is connected to a heat sink via a lower metal electrode.

[0019] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0020] The phase matching layer is located at the top of the P-type DBR reflector in the vertical cavity surface emitting laser working at low temperature and the vertical cavity surface emitting laser working at high temperature;

[0021] A multi-quantum well active region and a P-type DBR reflector are respectively arranged at two ends of the spacer layer;

[0022] The spacer layer is also arranged in the multi-quantum well active region and the N-type DBR reflector;

[0023] The spacer layer is located between the multi-quantum well active region and the P-type DBR reflector and the N-type DBR reflector, and is used to adjust the length of the resonant cavity.

[0024] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0025] The sensing layer includes a temperature sensor, a temperature model and a data-driven model;

[0026] The temperature model detects the temperature distribution prediction data inside the VCSEL light source under different working conditions by conducting multi-layer heat conduction on the VCSEL light source and the heat exchange with the external environment;

[0027] Methods for obtaining the temperature distribution inside the VCSEL light source include:

[0028] S1. Divide the VCSEL light source into N layers from bottom to top according to its physical structure, marked as layer 1 to layer N respectively;

[0029] S2. Obtain heat flux vector data and simplify it into one-dimensional heat conduction.

[0030]

[0031] in, is the heat flux density of each layer of the VCSEL light source, is the thermal conductivity, is the temperature of the VCSEL light source material layer, is the one-dimensional heat conduction direction;

[0032] S3. Output the predicted temperature distribution data inside the VCSEL light source through the data-driven model.

[0033] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0034] Data acquisition is used to receive temperature distribution data inside the VCSEL light source under different working conditions;

[0035] Data preprocessing includes data cleaning and normalization;

[0036] Multi-layer temperature prediction includes a multi-layer perception structure. Assume that the input layer has n temperature feature nodes inside the VCSEL light source, the hidden layer has L layers, and the number of nodes in the zth hidden layer is , where z=1,2,3,..., and the output layer has k nodes;

[0037] Randomly initialize the connection weight matrix W and bias vector b between each layer. For the connection between the zth layer and the z+1th layer, the dimension of the weight matrix W is , the bias vector The dimension is z;

[0038] The temperature distribution data inside the VCSEL light source is calculated and kernel operation is performed to further predict the temperature distribution data inside the VCSEL light source. The kernel operation expression is as follows:

[0039]

[0040] in, is the predicted value of the temperature distribution data inside the VCSEL light source, is the activation function, Y is the real-time temperature data of each layer inside the VCSEL light source, b is the bias, is the weight of the hidden layer z-1, is the bias of the hidden layer z-1;

[0041] The temperature distribution data set inside the entire VCSEL light source is calculated through a multi-layer temperature prediction process to obtain a predicted output multi-layer temperature matrix, whose dimension is the same as the target temperature value matrix, and each row corresponds to a predicted temperature value vector of a sample.

[0042] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0043] The predicted temperature inside the VCSEL light source is calculated by predicting the loss amount. The loss amount is obtained by calculating the difference between the predicted temperature value and the actual temperature value. The data-driven model is then corrected by loss gradient compensation. The loss calculation expression is as follows:

[0044]

[0045] in, is the loss value between the predicted temperature and the actual temperature inside the VCSEL light source, a is the number of VCSEL light source layers, b is the temperature of the corresponding layer, To predict the output of the multi-layer temperature matrix, is the actual temperature matrix, and M is the total number of data.

[0046] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0047] The weight of each part of the data-driven model is corrected by chaining, and the calculation expression is as follows:

[0048]

[0049] The weight of each layer is calculated in turn, and the weight of each layer is updated. The above steps are repeated for a certain number of iterations until the stopping condition is met.

[0050] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0051] The adaptive layer includes fuzzy reasoning, defuzzification, VCSEL light source control and control execution unit;

[0052] The light source fuzzy control receives the difference between the predicted VCSEL light source temperature and the pre-set high temperature threshold as the basic data, and uses the temperature change rate and optical power deviation as the input data of the light fuzzy control algorithm. According to fuzzy reasoning, the fuzzification of the VCSEL light source temperature variable and the optical power variable is output, and the fuzzy control rules are automatically compared. After defuzzification, the heat dissipation components and output light of the VCSEL light source are adjusted and controlled.

[0053] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0054] The calculation expression of defuzzification is as follows:

[0055]

[0056] in, is the membership coefficient, is the control rule for temperature difference or optical power deviation control adjustment, x is the input VCSEL light source temperature adjustment amount, X is the total range of temperature adjustment amount, It is the defuzzified VCSEL light source control instruction.

[0057] As a preferred solution of a high temperature adaptability VCSEL light source of the present invention, wherein:

[0058] The calculation expression for VCSEL light source control is as follows:

[0059]

[0060]

[0061] in, is the driving current adjustment value on the VCSEL light source electrode, To adjust the light intensity proportionality factor, To adjust the light intensity integral coefficient, To adjust the differential coefficient of light intensity, is the defuzzified VCSEL light source control instruction, t is the time, is the target light intensity, To predict light intensity

[0062] The control execution unit is used to receive VCSEL light source control instructions and control the VCSEL light source.

[0063] Beneficial effects of the present invention:

[0064] By connecting a low-temperature vertical-cavity surface-emitting laser and a high-temperature vertical-cavity surface-emitting laser in parallel and filling them with BCB materials, the light source can work normally in a wide temperature range. The temperature distribution data under different working conditions is collected, and pre-processed such as cleaning and normalization are performed. Then, the temperature is predicted by kernel calculation using a multi-layer perception structure. Finally, the model is reversely corrected based on the predicted loss, making the prediction of the temperature distribution inside the light source more and more accurate. Accurate temperature prediction provides a reliable basis for subsequent adaptive adjustment, helps to achieve precise temperature control, and efficiently and accurately regulates the light source, thereby ensuring that the light source can still stably and efficiently output lasers that meet the requirements in complex and changing temperature environments, improving the practical value of the light source and its applicability in different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0066] Figure 1 This is a structural diagram of a high temperature adaptability VCSEL light source of the present invention;

[0067] Figure 2 This is a simulation diagram of the spectrum and active region gain spectrum of a low-temperature VCSEL light source with high temperature adaptability at room temperature (23°C) of the present invention;

[0068] Figure 3 The spectrum of the high-temperature adaptable VCSEL light source of the present invention at room temperature (23°C) and the gain spectrum of the active region;

[0069] Figure 4 This is a simulation diagram of the PIV characteristics of a low-temperature VCSEL at an ambient temperature of -20°C, a high-temperature adaptability VCSEL light source of the present invention;

[0070] Figure 5 This is a simulation diagram of the PIV characteristics of a high-temperature VCSEL light source with high temperature adaptability at an ambient temperature of 80°C;

[0071] Figure numerals: 1. metal electrode; 2. passivation layer; 3. P-type DBR reflector; 4. oxide layer; 5. multi-quantum well active region; 6. N-type DBR reflector; 7. N-type substrate layer; 8. lower metal electrode; 9. spacer layer; 10. phase matching layer; 11. heat sink; 12. BCB material; 13. optical coupling into optical fiber; 14. optical fiber combiner. DETAILED DESCRIPTION

[0072] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0073] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0074] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0075] Embodiment 1:

[0076] like Figure 1 As shown, a high temperature adaptability VCSEL light source includes:

[0077] One end of the light combiner 14 is connected to the metal electrode 1 through the light coupling optical fiber 13, and one end of the metal electrode 1 is sequentially provided with a passivation layer 2, a P-type DBR reflector 3, an oxide layer 4, a multi-quantum well active region 5, an N-type DBR reflector 6, an N-type substrate layer 7, and a lower metal electrode 8;

[0078] The VCSEL light source includes a low-temperature vertical cavity surface emitting laser and a high-temperature vertical cavity surface emitting laser connected in parallel, and the low-temperature vertical cavity surface emitting laser and the high-temperature vertical cavity surface emitting laser are filled with a BCB material 12;

[0079] A high-temperature VCSEL is connected in parallel with a low-temperature VCSEL, and their output lasers are combined into one parallel output through two directly coupled single-mode optical fibers via an external fiber combiner, so that the optical power of the VCSEL light source can compensate each other at low and high temperatures, ultimately achieving stable light output over a wide temperature range.

[0080] In order to match the wavelengths of the two lasers, the VCSELs working at low temperature and high temperature are designed with similar cavity lengths and DBR structures. The gain peak of the active region of the VCSEL working at low temperature at room temperature is designed to be at the short-wave position of the cavity mode, and the gain peak of the active region of the VCSEL working at high temperature at room temperature is designed to be at the long-wave position of the cavity mode. In this way, when the ambient temperature decreases or increases, the gain spectrum is blue-shifted and red-shifted relative to the cavity mode, respectively, so that the two devices obtain higher mode gain at low temperature and high temperature, respectively. By increasing the thickness of the quantum well or quantum dot layer in the active region and reducing the content of the In component to reduce the lattice mismatch, the material gain spectrum is flattened, thereby increasing the wavelength detuning of the high-temperature VCSEL and ensuring that it can work normally at higher temperatures.

[0081] Furthermore, the surface and sidewalls of the VCSEL are electrically isolated by evaporating a silicon oxide or silicon nitride insulating layer, and at the same time, the outside air is prevented from penetrating into the gap of the oxide layer to form continuous oxidation after the VCSEL works at high temperature for a long time. After the high-temperature and low-temperature VCSELs are prepared, they are welded to the same metal heat sink substrate, and the interval is set to be greater than 100μm to reduce thermal crosstalk. The interval is filled with BCB material, and finally the upper electrodes of the two VCSEL devices are connected by evaporating gold;

[0082] High temperature vertical cavity surface emitting lasers, including,

[0083] One end of the passivation layer 2 is connected to the metal electrode 1, and the other end is provided with a P-type DBR reflector 3;

[0084] An oxide layer 4 is provided at the other end of the P-type DBR reflector 3, and the other end of the oxide layer 4 is connected to an N-type DBR reflector 6 via a multi-quantum well active region 5;

[0085] The other end of the N-type DBR reflector 6 is provided with an N-type substrate layer 7, and the N-type substrate layer 7 is connected to a heat sink 11 through a lower metal electrode 8

[0086] One end of the light combiner 14 is parallelly provided with a light coupling optical fiber 13 connected to the phase matching layer 10;

[0087] The sensing layer monitors and predicts the temperature of the VCSEL light source by establishing a temperature model;

[0088] Adaptive layer, adaptively adjusts the intensity of VCSEL light source through temperature stratification.

[0089] The phase matching layer 10 is located at the top of the P-type DBR reflector 3 in the vertical cavity surface emitting laser working at low temperature and the vertical cavity surface emitting laser working at high temperature;

[0090] The two ends of the spacer layer 9 are respectively provided with a multi-quantum well active region 5 and a P-type DBR reflector 3;

[0091] The spacer layer 9 is also arranged between the multi-quantum well active region 5 and the N-type DBR reflector 6;

[0092] The spacer layer 9 is located between the multi-quantum well active region 5 and the P-type DBR reflector 3 and the N-type DBR reflector 6, and is used to adjust the resonant cavity length;

[0093] Further, there are a plurality of spacer layers 9 and the spacer layers 9 are present on both the top of the low-temperature VCSEL and the top of the high-temperature VCSEL.

[0094] Further, such as Figure 1 The VCSEL light source of the present invention includes a low-temperature (left) and a high-temperature (right) vertical cavity surface emitting laser connected in parallel. Both VCSELs include an upper metal electrode 1, a passivation layer 2, a P-type DBR reflector 3, an oxide layer 4, a multi-quantum well active region 5, an N-type DBR reflector 6, an N-type substrate layer 7, a lower metal electrode 8, a spacer layer 9, and a phase matching layer 10;

[0095] Furthermore, the lower electrodes of the two VCSELs are welded on the same heat sink 11, and the central wavelengths of the spectra of the two VCSELs are set near 980nm. The quantum well material of the active region of the low-temperature VCSEL uses In0.23Ga0.77As material, and the active region of the high-temperature VCSEL uses In0.18Ga0.82As material with a lower In component so that the material gain peak is located at the short-wave position of the central wavelength. The BCB material 12 is used to fill the gap between the two VCSELs, and the light outlet couples the output light into the optical fiber 13 by direct coupling. The two light beams are combined by the optical fiber combiner 14 and output as one channel, so that the output optical power is approximately the sum of the output optical powers of the two VCSELs.

[0096] Furthermore, the low-temperature VCSEL uses an oxidation aperture of 6 microns, and the high-temperature VCSEL uses an oxidation aperture of 10 microns for current limitation, wherein the low-temperature VCSEL uses a single oxide layer limitation at the top of the active region, and the oxide layer material is Al0.98Ga0.02As material, and the high-temperature VCSEL is provided with an oxide layer at the top and bottom of the active region, wherein the top oxide layer material is Al0.97Ga0.03As material, and the bottom oxide layer material is Al0.98Ga0.02As material. The device involved is grown on an n-type GaAs substrate, and the high and low refractive index materials of the DBR reflector are GaAs material and Al0.9Ga0.1As material, respectively.

[0097] Figure 2 This is a simulation diagram of the correspondence between the low-temperature spectrum of the VCSEL at room temperature (23°C) and the gain spectrum of the active area;

[0098] Figure 3This is a simulation diagram of the correspondence between the high temperature spectrum of VCSEL at room temperature (23°C) and the gain spectrum of the active area;

[0099] Figure 4 PIV characteristics of low-temperature VCSEL at -20°C ambient temperature;

[0100] Figure 5 PIV characteristics of high temperature VCSEL at 80°C ambient temperature;

[0101] Further, a specific example of setting parameters of a high temperature adaptable VCSEL light source is provided, including

[0102] The beam divergence angle of VCSEL is directly related to the thickness of the resonant cavity. The thicker the resonant cavity, the smaller the beam divergence angle, and thus the larger its numerical aperture and the higher the coupling efficiency with the optical fiber. However, the increase in cavity length will often lead to a decrease in the longitudinal mode spacing and a decrease in the high-frequency performance of the device. Therefore, after comprehensive consideration, a resonant cavity length between 2λ and 5λ is finally selected.

[0103] Both low-temperature and high-temperature VCSELs limit the lateral diffusion of current through the oxide layer. Since the active region gain is high at low temperatures, it is easy to obtain high light output power and efficiency. The gain is reduced at high temperatures. Considering the power matching at high and low temperatures, the oxide aperture size of the low-temperature VCSEL is selected to be ≤8μm to appropriately increase the device differential resistance and reduce the light output power; at the same time, the smaller oxide aperture can effectively reduce the number of transverse modes of the device and improve the beam quality. For high-temperature VCSELs, a small oxide aperture will seriously affect the heat dissipation of the device. Therefore, its oxide aperture is set to ≥8μm to improve its heat dissipation capacity and avoid exceeding the thermal damage threshold when working at high temperatures, resulting in device damage. In addition, considering the lower gain of the high-temperature VCSEL, this design sets an oxide layer on the upper and lower sides of its active region to improve the current limiting capability and reduce the device threshold. In the actual device preparation process, it is usually difficult to make the mesa of VCSEL steep, resulting in the lower oxide layer being wider than the upper oxide layer. To this end, the Al component content of the lower oxide layer is designed to be slightly higher than that of the upper oxide layer to increase its wet oxygen oxidation rate, so that the final upper and lower oxide apertures are of similar size to optimize the current limiting effect. The oxide layer is designed to be located at the node of the VCSEL standing wave field to reduce the current crowding effect at the edge of the oxide layer.

[0104] The external driving circuit supplies the device with a current greater than the sum of the maximum threshold currents of the two VCSELs in the full temperature range to drive the device to work normally. In a low-temperature environment, the low-temperature VCSEL achieves high-power output, while the high-temperature VCSEL has a lower power; in a high-temperature environment, the power of the low-temperature VCSEL decreases, while the high-temperature VCSEL achieves a higher-power optical output; at room temperature, both lasers obtain moderate optical output power. The two VCSELs are connected to the optical fiber by direct coupling, and after being combined by the optical fiber combiner, they are merged into the same optical fiber for output. In this way, the device can achieve relatively constant optical power output in low-temperature, room-temperature, and high-temperature environments.

[0105] Embodiment 2:

[0106] A high temperature adaptable VCSEL light source, comprising:

[0107] The sensing layer monitors and predicts the temperature of the VCSEL light source by establishing a temperature model;

[0108] Among them, the sensing layer includes temperature sensors, temperature models and data-driven models;

[0109] Furthermore, the temperature sensor selects a miniature high-precision thermistor as the temperature sensor, and based on the structural characteristics and thermal conductivity characteristics of the VCSEL light source, multiple thermistors are distributed and arranged at different key positions;

[0110] For example:

[0111] Several thermistors are evenly spaced on the surface of the N-type substrate layer 7. Since the substrate layer is closely connected to the entire VCSEL chip and conducts the heat generated by the chip during operation, the approximate temperature of the entire chip can be obtained more directly through the thermistors here. 3-5 thermistors can be arranged here to form a preliminary temperature monitoring point network.

[0112] On the surface of the heat sink 11 near the spacer layer 9, several thermistors (e.g., 2-4) are reasonably arranged along the edge and center area of ​​the heat sink. The heat sink is mainly used for heat dissipation. Monitoring its temperature change helps to understand the heat dissipation efficiency and the heat distribution on the entire heat dissipation channel, thereby indirectly reflecting the thermal state of the VCSEL light source when it is working.

[0113] At appropriate locations around the multi-quantum well active region 5, extremely small thermistors (1-2) are embedded through micro-nano processing technology, because the multi-quantum well active region is the core area for generating lasers, and the temperature here has a great influence on the performance of the light source. Although it is difficult to arrange a large number of sensors due to space limitations, even a small number of high-precision sensors can obtain key temperature data here, which helps to accurately grasp the thermal environment of the active region;

[0114] Build a multiplexed temperature acquisition circuit, connect each thermistor to the circuit, provide a stable driving current for each thermistor through a constant current source, and use a high-precision analog-to-digital converter (ADC) to convert the voltage change caused by temperature change at both ends of the thermistor into a digital signal. Select an ADC with a resolution of at least 12 bits or even higher to ensure that the voltage difference corresponding to small temperature changes can be accurately distinguished, and the accuracy of temperature measurement is within ±0.1°C. The acquisition circuit is equipped with a microcontroller (such as a low-power, high-performance single-chip microcomputer). The microcontroller collects the temperature data corresponding to each thermistor in turn at a certain time interval (for example, every 100 milliseconds), and temporarily stores this data in the internal cache area;

[0115] Furthermore, the temperature model detects the temperature distribution inside the VCSEL light source under different working conditions by conducting multi-layer heat conduction to the VCSEL light source and the heat exchange with the external environment;

[0116] First, the VCSEL light source is divided into N layers from bottom to top according to its physical structure, marked as layer 1 to layer N, each layer has its own specific material properties, for example, the N-type substrate layer 7, the multi-quantum well active region 5, etc. correspond to different layers, each with different thermal parameters;

[0117] Secondly, according to Fourier's law, the heat flux density vector data is obtained and simplified into one-dimensional heat conduction.

[0118]

[0119] in, is the heat flux density of each layer of the VCSEL light source, is the thermal conductivity, is the temperature of the VCSEL light source material layer, is the one-dimensional heat conduction direction;

[0120] The transient change of temperature over time is involved, which is simplified for analysis first, and can be expanded to transient situations later, etc., all of which follow the principle of energy conservation, that is, thermal balance. This embodiment provides a specific implementation method to solve the steady-state change situation. The specific parameters should refer to the specific practical application, including temperature changes, material selection, heat loss and other factors;

[0121] The data-driven model receives the temperature distribution inside the VCSEL light source under different working conditions, predicts the temperature of different parts of the VCSEL light source, and continuously verifies and updates the model to ensure that its prediction accuracy continues to improve with the increase in data volume and the enrichment of working scenarios, and finally forms a reliable temperature model that can be used to monitor and predict the temperature of the VCSEL light source in real time;

[0122] Furthermore, the data-driven model includes data acquisition, data preprocessing, multi-layer temperature prediction, and reverse optimization of predicted losses;

[0123] Data acquisition is used to receive temperature distribution data inside the VCSEL light source under different working conditions;

[0124] Data preprocessing includes data cleaning and normalization;

[0125] Specifically, data cleaning calculates the mean and standard deviation of the temperature distribution data inside the VCSEL light source under different working conditions, and removes outliers by setting a threshold (for example, according to the 3-times standard deviation principle, judging whether the temperature inside the VCSEL light source under a certain working state of a sample meets the 3-times standard deviation principle, and if so, determining it as an outlier and removing the entire row of data corresponding to the sample), to obtain a cleaned data set;

[0126] Furthermore, eigenvalues ​​are extracted from the temperature distribution data set inside the cleaned VCSEL light source, and eigenvectors corresponding to the eigenvalues ​​are calculated to construct a feature matrix, and the normalized eigenvalues ​​are calculated based on the minimum-maximum normalization of the input feature matrix;

[0127] Multi-layer temperature prediction includes a multi-layer perception structure. Assume that the input layer has n nodes (corresponding to the number of temperature features inside the input VCSEL light source), the hidden layer has L layers, and the number of nodes in the zth hidden layer is (z=1,2,3,...), the output layer has k nodes;

[0128] The connection weight matrix W and bias vector b between each layer are randomly initialized. For the connection between the zth layer and the z+1th layer, the dimension of the weight matrix W is , the bias vector The dimension is For example, the weight matrix W0 of the first hidden layer (z=0, the input layer is considered as layer 0) connects n nodes in the input layer to the first hidden layer. nodes, whose dimensions are n;

[0129] The temperature distribution data inside the VCSEL light source is calculated and kernel operation is performed to further predict the temperature distribution data inside the VCSEL light source. The kernel operation expression is as follows:

[0130]

[0131] in, is the predicted value of the temperature distribution data inside the VCSEL light source, is the activation function, Y is the real-time temperature data of each layer inside the VCSEL light source, b is the bias, is the weight of the hidden layer z-1, is the bias of the hidden layer z-1;

[0132] The temperature distribution data set inside the entire VCSEL light source is calculated through the multi-layer temperature prediction process, and a predicted output multi-layer temperature matrix can be obtained. Its dimension is the same as the target temperature value matrix, and each row corresponds to a predicted temperature value vector of a sample;

[0133] The predicted temperature inside the VCSEL light source is calculated by predicting the loss amount. The loss amount is obtained by calculating the difference between the predicted temperature value and the actual temperature value. The data-driven model is then corrected by loss gradient compensation. The loss calculation expression is as follows:

[0134]

[0135] in, is the loss value, a is the number of VCSEL light source layers, b is the temperature of the corresponding layer, To predict the output of the multi-layer temperature matrix, is the actual temperature matrix, M is the total number of data;

[0136] The weight of each part of the data-driven model is adjusted through chaining, and the calculation expression is as follows:

[0137]

[0138] The weights of each layer are calculated in turn, and the weights of each layer are updated. The above steps are repeated for a certain number of iterations until the stopping condition is met (such as the loss function value of the validation set no longer decreases significantly).

[0139] Embodiment three:

[0140] Adaptive layer, adaptively adjusts the intensity of VCSEL light source through temperature stratification;

[0141] An optical power detector is set at the output end of the light beam combiner 14. The optical power detector uses a photodiode with high sensitivity, wide dynamic range and fast response characteristics. It can accurately measure the optical power output from the VCSEL light source after the light beam combiner is combined, and convert the optical power signal into an electrical signal in real time. Design a corresponding signal conditioning circuit to amplify and filter the weak electrical signal output by the photodiode, and input the processed signal into the subsequent control module to ensure that the optical power signal received by the control module has sufficient accuracy and stability, so as to accurately judge the difference between the real-time change of optical power and the preset target optical power;

[0142] The adaptive layer also includes a control strategy output unit, a VCSEL light source control and a control unit;

[0143] The control strategy output unit is used to divide the temperature range into multiple stratified intervals and adaptively adjust the algorithm according to the performance changes of the VCSEL light source in different temperature ranges and application requirements;

[0144] Furthermore, according to the performance changes of VCSEL light sources in different temperature ranges and application requirements, the temperature range is divided into multiple hierarchical intervals, for example: low temperature interval (T < T1, assuming T1 is a low temperature threshold), in which the performance of the light source is relatively stable, but the light output power may be slightly low, and the driving current needs to be appropriately increased to enhance the light intensity; medium temperature interval (T1 ≤ T < T2), which is the main interval for the normal operation of the light source, where the light power and efficiency are in a good balance state, and relatively stable driving conditions can be maintained; high temperature interval (T ≥ T2), when the temperature is too high, the performance of the light source may drop sharply or even be damaged. At this time, it is necessary to quickly reduce the driving current or take heat dissipation enhancement measures to protect the light source and maintain a reasonable light output intensity;

[0145] The adaptive adjustment algorithm is based on the above-mentioned temperature stratification intervals and uses a fuzzy control algorithm to achieve adaptive adjustment of the intensity of the VCSEL light source. The stratification interval of the temperature value predicted by the temperature model is used as the basis for judgment. When in the low temperature interval, the PID controller gradually increases the driving current applied to the metal electrode 1 and the lower metal electrode 8 according to the deviation between the optical power and the target optical power, so that the injection current of the VCSEL light source increases, thereby improving the light output intensity. At the same time, the optical power changes are monitored in real time to prevent damage to the light source caused by over-driving; in the medium temperature interval, a relatively stable driving current is maintained, and only fine-tuned according to slight fluctuations in optical power to ensure the stability of light output; after entering the high temperature interval, the light source fuzzy control algorithm makes a comprehensive judgment based on multiple factors such as the degree to which the temperature exceeds the high temperature threshold and the decrease in optical power, and quickly reduces the driving current, and at the same time, sends a signal to the heat dissipation system;

[0146] A control signal is sent to enhance heat dissipation, and the normal driving state and light output intensity are gradually restored after the temperature drops back to the appropriate range. This hierarchical adaptive control strategy enables reasonable adjustment and stable output of the VCSEL light source intensity under different temperature environments.

[0147] The light source fuzzy control algorithm receives the difference between the predicted VCSEL light source temperature and the pre-set high temperature threshold as the basic data, and uses the temperature change rate and optical power deviation as the input data of the light fuzzy control algorithm. According to fuzzy reasoning, the fuzzification of the VCSEL light source temperature variable and the optical power variable is output, and the fuzzy control rules are automatically compared to adjust and control the heat dissipation components and output light of the VCSEL light source.

[0148] Furthermore, the rule base includes but is not limited to: when the temperature deviation is large and is still increasing rapidly, and the optical power deviation is also large and the optical power is seriously insufficient (much lower than the target optical power), it is necessary to significantly reduce the driving current to protect the light source, and significantly increase the speed of the cooling fan to enhance heat dissipation and reduce the temperature as soon as possible;

[0149] If the temperature deviation is small, the temperature change rate is close to zero (tending to stabilize at a state slightly above the high temperature threshold), and the optical power is only slightly lower than the target value, then you only need to slightly reduce the drive current and slightly increase the cooling fan speed to fine-tune the temperature and optical power;

[0150] When the temperature deviation is negative (lower than the high temperature threshold and the deviation is small), but the temperature drops quickly, the optical power is higher than the target value and the deviation is medium, the drive current can be slightly increased to increase the optical power, and the cooling fan speed can be slightly reduced to prevent the temperature from being too low and affecting the light source performance;

[0151] Furthermore, fuzzy reasoning is to infer the fuzzy value of the output variable through the Mamdani reasoning method based on the fuzzy value of the input variable and the fuzzy control rule base, for example:

[0152] For the precise values ​​of given input variables (specific values ​​of temperature deviation, temperature deviation change rate and optical power deviation obtained through actual measurement), firstly, their membership on their respective corresponding fuzzy subsets is determined through the previously defined temperature difference and optical power deviation. The membership is understood as the deviation rate.

[0153] Then, for each fuzzy control rule, the input temperature variable membership is "AND" operated (usually by taking the minimum value) to obtain the excitation intensity (or trigger intensity) of the rule. For example, for a certain rule, the membership of the temperature deviation in the "positive large (PB)" subset is 0.6, the membership of the temperature deviation change rate in the "positive large (PB)" subset is 0.8, and the membership of the optical power deviation in the "negative large (NB)" subset is 0.7, then the excitation intensity of this rule is the minimum membership of 0.6.

[0154] Then, according to the incentive strength of each rule, the conclusion part of the rule (the fuzzy subset corresponding to the output variable) is “truncated” to obtain the fuzzy implication relationship of the output variable corresponding to each rule.

[0155] Each rule establishes a fuzzy control rule base based on the thermal characteristics and optical power characteristics of the VCSEL light source. The rule is usually in the form of "IF (condition) THEN (conclusion)";

[0156] Finally, the fuzzy implication relations of the output variables corresponding to all rules are “OR” operated (usually by taking the maximum value) to obtain the fuzzy set of the total output variables;

[0157] The output variable obtained by fuzzy reasoning is in the form of a fuzzy set, which needs to be converted into an exact value so that it can be actually applied to VCSEL light source temperature regulation or optical power regulation. The defuzzification calculation expression is as follows:

[0158]

[0159] in, is the membership coefficient, is the control rule for temperature difference or optical power deviation control adjustment, x is the input VCSEL light source temperature adjustment amount, X is the total range of temperature adjustment amount, is the defuzzified VCSEL light source control instruction;

[0160] The defuzzification calculation includes the numerator part and the denominator ;

[0161] Molecular part Consider each possible control value and its degree of conformity under the current fuzzy reasoning result, and then perform weighted summation;

[0162] Furthermore, the denominator Integrating the membership coefficients within the entire value range is essentially calculating the sum of the membership coefficients of all possible value points. It plays a normalization role, so that the defuzzified result can reasonably fall within the value range of the output variable, ensuring that the value of the calculated control instruction is in line with the actual control range and reasonably reflects the fuzzy reasoning result.

[0163] By dividing the numerator by the denominator, an accurate value that best represents the overall situation of the fuzzy set is determined. This value is the control instruction used to actually adjust the temperature or optical power of the VCSEL light source. For example, the accurate value of the driving current adjustment amount can directly act on the driving circuit of the VCSEL light source to achieve accurate current adjustment, thereby affecting the temperature and optical power; the accurate value of the cooling fan speed adjustment amount can control the actual speed of the cooling fan and assist in adjusting the temperature, etc.

[0164] The calculation expression for VCSEL light source control is as follows:

[0165]

[0166]

[0167] in, is the driving current adjustment value on the VCSEL light source electrode, To adjust the light intensity proportionality factor, To adjust the light intensity integral coefficient, To adjust the differential coefficient of light intensity, is the defuzzified VCSEL light source control instruction, t is the time, is the target light intensity, To predict light intensity;

[0168] The further defuzzified VCSEL light source control instruction only represents a logic, and how to output the VCSEL light source control instruction is output by the adaptive layer.

[0169] The detailed design of the sensing layer and the adaptive layer can effectively monitor and predict the temperature of the VCSEL light source and adaptively adjust the light source intensity according to the temperature conditions, thereby improving the working stability and performance of the VCSEL light source under various complex working conditions.

[0170] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only two embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible, for example, the size, scale, structure, shape and ratio of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc., without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. Any "device plus function" clause is intended to cover the structure of the execution function described in this article, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiment. Therefore, the invention is not limited to a specific embodiment, but extends to several modifications still falling within the scope of the appended claims.

[0171] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment may not be described (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those features that are not relevant to implementing the invention).

[0172] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0173] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high temperature adaptability VCSEL light source, characterized in that: include: One end of the light beam combiner (14) is connected to a metal electrode (1) via a light coupling optical fiber (13); one end of the metal electrode (1) is provided with a passivation layer (2), a P-type DBR reflector (3), an oxide layer (4), a multi-quantum well active region (5), an N-type DBR reflector (6), an N-type substrate layer (7), and a lower metal electrode (8) in sequence; One end of the light beam combiner (14) is parallelly provided with a light coupling optical fiber (13) connected to the phase matching layer (10); The sensing layer monitors and predicts the temperature of the VCSEL light source by establishing a temperature model; Adaptive layer, adaptively adjusts the intensity of VCSEL light source through temperature stratification.

2. A high temperature adaptability VCSEL light source according to claim 1, characterized in that: The VCSEL light source comprises a low-temperature vertical cavity surface emitting laser and a high-temperature vertical cavity surface emitting laser connected in parallel, wherein the low-temperature vertical cavity surface emitting laser and the high-temperature vertical cavity surface emitting laser are filled with a BCB material (12); The high-temperature vertical cavity surface emitting laser comprises: One end of the passivation layer (2) is connected to the metal electrode (1), and the other end is provided with a P-type DBR reflector (3); An oxide layer (4) is provided at the other end of the P-type DBR reflector (3), and the other end of the oxide layer (4) is connected to an N-type DBR reflector (6) via a multi-quantum well active region (5); An N-type substrate layer (7) is provided at the other end of the N-type DBR reflector (6), and the N-type substrate layer (7) is connected to a heat sink (11) via a lower metal electrode (8).

3. A high temperature adaptability VCSEL light source according to claim 2, characterized in that: The phase matching layer (10) is located at the top of a P-type DBR reflector (3) in a vertical cavity surface emitting laser operating at a low temperature and in the vertical cavity surface emitting laser operating at a high temperature; A multi-quantum well active region (5) and a P-type DBR reflector (3) are respectively arranged at two ends of the spacer layer (9); The spacer layer (9) is also arranged between the multi-quantum well active region (5) and the N-type DBR reflector (6); The spacer layer (9) is located between the multi-quantum well active region (5) and the P-type DBR reflector (3) and the N-type DBR reflector (6), and is used to adjust the resonant cavity length.

4. A high temperature adaptability VCSEL light source according to claim 3, characterized in that: The sensing layer includes a temperature sensor, a temperature model and a data-driven model; The temperature model detects the temperature distribution prediction data inside the VCSEL light source under different working conditions by conducting multi-layer heat conduction on the VCSEL light source and the heat exchange with the external environment; Methods for obtaining the temperature distribution inside the VCSEL light source include: S1. Divide the VCSEL light source into N layers from bottom to top according to its physical structure, marked as layer 1 to layer N respectively; S2. Obtain heat flux vector data and simplify it into one-dimensional heat conduction. ； in, is the heat flux density of each layer of the VCSEL light source, is the thermal conductivity, is the temperature of the VCSEL light source material layer, is the one-dimensional heat conduction direction; S3. Output the predicted temperature distribution data inside the VCSEL light source through the data-driven model.

5. A high temperature adaptability VCSEL light source according to claim 4, characterized in that: The data-driven model includes data acquisition, data preprocessing, multi-layer temperature prediction, and reverse optimization of predicted losses; Data acquisition is used to receive temperature distribution data inside the VCSEL light source under different working conditions; Data preprocessing includes data cleaning and normalization; Multi-layer temperature prediction includes a multi-layer perception structure. Assume that the input layer has n temperature feature nodes inside the VCSEL light source, the hidden layer has L layers, and the number of nodes in the zth hidden layer is , where z=1,2,3,..., and the output layer has k nodes; Randomly initialize the connection weight matrix W and bias vector b between each layer. For the connection between the zth layer and the z+1th layer, the dimension of the weight matrix W is , the bias vector The dimension is z; The temperature distribution data inside the VCSEL light source is calculated and kernel operation is performed to further predict the temperature distribution data inside the VCSEL light source. The kernel operation expression is as follows: ； in, is the predicted value of the temperature distribution data inside the VCSEL light source, is the activation function, Y is the real-time temperature data of each layer inside the VCSEL light source, b is the bias, is the weight of the hidden layer z-1, is the bias of the hidden layer z-1; The temperature distribution data set inside the entire VCSEL light source is calculated through a multi-layer temperature prediction process to obtain a predicted output multi-layer temperature matrix, whose dimension is the same as the target temperature value matrix, and each row corresponds to a predicted temperature value vector of a sample.

6. A high temperature adaptability VCSEL light source according to claim 5, characterized in that: The predicted temperature inside the VCSEL light source is calculated by predicting the loss amount. The loss amount is obtained by calculating the difference between the predicted temperature value and the actual temperature value. The data-driven model is then corrected by loss gradient compensation. The loss calculation expression is as follows: ； in, is the loss value between the predicted temperature and the actual temperature inside the VCSEL light source, a is the number of VCSEL light source layers, b is the temperature of the corresponding layer, To predict the output of the multi-layer temperature matrix, is the actual temperature matrix, and M is the total number of data.

7. A high temperature adaptability VCSEL light source according to claim 6, characterized in that: The weight of each part of the data-driven model is corrected by chaining, and the calculation expression is as follows: ； The weight of each layer is calculated in turn, and the weight of each layer is updated. The above steps are repeated for a certain number of iterations until the stopping condition is met.

8. The high temperature adaptability VCSEL light source according to claim 7, characterized in that: The adaptive layer includes fuzzy reasoning, defuzzification, VCSEL light source control and control execution unit; The light source fuzzy control receives the difference between the predicted VCSEL light source temperature and the pre-set high temperature threshold as the basic data, and uses the temperature change rate and optical power deviation as the input data of the light fuzzy control algorithm. According to fuzzy reasoning, the fuzzification of the VCSEL light source temperature variable and the optical power variable is output, and the fuzzy control rules are automatically compared. After defuzzification, the heat dissipation components and output light of the VCSEL light source are adjusted and controlled.

9. The high temperature adaptability VCSEL light source according to claim 8, characterized in that: The calculation expression of defuzzification is as follows: ； in, is the membership coefficient, is the control rule for temperature difference or optical power deviation control adjustment, x is the input VCSEL light source temperature adjustment amount, X is the total range of temperature adjustment amount, It is the defuzzified VCSEL light source control instruction.

10. The high temperature adaptability VCSEL light source according to claim 9, characterized in that: The calculation expression for VCSEL light source control is as follows: ； ； in, is the driving current adjustment value on the VCSEL light source electrode, To adjust the light intensity proportionality factor, To adjust the light intensity integral coefficient, To adjust the differential coefficient of light intensity, is the defuzzified VCSEL light source control instruction, t is the time, is the target light intensity, To predict light intensity The control execution unit is used to receive VCSEL light source control instructions and control the VCSEL light source.

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