Aging compensation method for optical device

Abstract

The invention discloses an aging compensation method for an optical device, and belongs to the technical field of optical device power compensation. The method comprises the following steps: constructing a statistical prediction model, and calculating a theoretical compensation amount of a driving current of a to-be-compensated optical device at a t moment by using the statistical prediction model; constructing a real-time feedback model, and calculating the feedback compensation amount of the driving current of the to-be-compensated optical device at the t moment by using the real-time feedback model; establishing a weighting function based on the life time inflection point of the optical device; the theoretical compensation amount and the feedback compensation amount are subjected to weighted fusion through a weighting function, and the final fusion compensation amount of the driving current of the to-be-compensated optical device at the t moment is obtained; and when the ratio of the slope efficiency at the t moment to the initial slope efficiency is less than 0.95 and the final fusion compensation amount is within the compensation boundary condition, compensating the driving current of the to-be-compensated optical device at the t moment based on the final fusion compensation amount. While the economic benefit of the optical device is improved, a better use effect of the optical device can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of optical device power compensation, and particularly to an aging compensation method for an optical device. Background Art

[0002] The most important working unit in an optical device is a semiconductor laser (LD, Laser Diode), and its working characteristics are very sensitive to the junction temperature. Specifically, as the junction temperature increases, the threshold current of the LD increases and the efficiency decreases, resulting in the aging of the optical device. Specifically, the aging failure of the optical device is usually caused by the growth of defects in the internal active region. Therefore, the performance of the optical device will slowly decline with the increase of the working time, such as the decrease of power and the decrease of voltage. Generally speaking, under normal working conditions, when the working current or output optical power of the optical device fluctuates by 20%, it is judged that the working life of the optical device fails.

[0003] In related technologies, the methods for dealing with the failure of the working life of an optical device mainly include the following two: one is to directly replace the optical device or the optical module itself; the other is to ensure a good working environment for the optical device or the optical module, such as increasing heat dissipation measures and adding a semiconductor cooler, etc., to reduce the influence of the increase of the junction temperature on the life of the optical device by reducing the temperature, thereby prolonging the service life of the optical device and the optical module.

[0004] However, the former does not consider the reusability of the module or device, that is, the remaining hardware of the failed device or module does not fail, resulting in poor economic benefits; the latter reduces the junction temperature by increasing heat dissipation and a semiconductor cooler. Although it can delay the aging of the optical device, it lacks quantitative detection feedback and compensation means, and the actual use effect of the optical device is not good. Summary of the Invention

[0005] The main purpose of the present invention is to provide an aging compensation method for an optical device, aiming to solve the technical problems of poor economic benefits and poor device use effect existing in related technologies when dealing with the aging problem of an optical device.

[0006] To achieve the above object, the present invention provides an aging compensation method for an optical device, and the method includes the following steps:

[0007] S1, by collecting the aging experiment data of a test optical device, constructing a statistical prediction model, and using the statistical prediction model to calculate the theoretical compensation amount of the drive current of the optical device to be compensated at time t;

[0008] S2, by the step response test result of the test optical device, constructing a real-time feedback model, and using the real-time feedback model to calculate the feedback compensation amount of the drive current of the optical device to be compensated at time t;

[0009] S3. Based on the inflection point of the lifetime of the optical device, a weight function is established; the theoretical compensation amount and the feedback compensation amount are weighted and fused through the weight function to obtain the final fused compensation amount of the drive current of the optical device to be compensated at time t.

[0010] S4. When the ratio of the slope efficiency at time t to the initial slope efficiency is less than 0.95 and the final fused compensation amount is within the compensation boundary condition, the drive current of the optical device to be compensated at time t is compensated based on the final fused compensation amount.

[0011] In the present invention, the theoretical compensation amount of the drive current of the optical device to be compensated at time t is calculated through a statistical prediction model, and then the feedback compensation amount at time t is calculated through a real-time feedback model. Thus, the two are weighted and fused by a weight function to obtain the final fused compensation amount, achieving the effect of real-time correction of the theoretical compensation amount by the feedback compensation amount, so as to avoid overcompensation of the drive current from accelerating the aging of the optical device and realize precise and controllable compensation of the drive current. On this basis, by establishing a compensation boundary condition and finely restricting the compensation amount, the negative impact brought by overcompensation can be further avoided. Therefore, while extending the service life of the optical device, the present invention can perform real-time correction on the compensation amount of the drive current according to real-time feedback, so as to precisely compensate the drive current. It can be seen that the present invention can ensure better use effects of the optical device while improving economic benefits. Description of the Drawings

[0012] Figure 1 is a schematic flowchart of an embodiment of the aging compensation method for the optical device of the present invention;

[0013] Figure 2 is a schematic detailed flowchart of an embodiment of the aging compensation method for the optical device of the present invention.

[0014] The realization, functional characteristics and advantages of the object of the present invention will be further described with reference to the embodiments and the drawings. Detailed Embodiments

[0015] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] The inventive concept of the present application will be further elaborated below in combination with some specific embodiments and specific implementation manners.

[0017] The embodiment of the present invention provides an aging compensation method for an optical device, referring to Figure 1 , Figure 1 is a schematic flowchart of the first embodiment of an aging compensation method for an optical device of the present invention.

[0018] In this embodiment, the aging compensation method for the optical device includes the following steps:

[0019] Step S1: By collecting the aging experiment data of the test optical device, construct a statistical prediction model, and use the statistical prediction model to calculate the theoretical compensation amount of the drive current of the optical device to be compensated at time t.

[0020] It is worth mentioning that in this embodiment, the test optical device is a new optical device used for aging tests, and the optical device to be compensated is an optical device after normal use. Among them, the aging test refers to placing the test optical device in a specific aging environment (such as a temperature of 85 °C, a humidity of 85%, or a large current) to work, accelerating its aging, and measuring the key performance parameters of the test optical device (including but not limited to the actual output optical power, the actual drive current, and the actual threshold current).

[0021] As Figure 2 shown, the step S1 specifically includes the following steps:

[0022] Step S11: Based on the aging test data of multiple test optical devices, construct a statistical prediction model through least squares fitting calculation.

[0023] The step S11 specifically includes:

[0024] Collect the actual output power P out and the actual drive current I of multiple test optical devices at different aging time points as the aging experiment data.

[0025] Based on the aging experiment data, calculate the threshold current I th (t) at the corresponding time point through the relational expression fitting of the output optical power and the drive current; the relational expression of the output optical power and the drive current:

[0026] ;

[0027] Among them, P out (t) represents the output optical power at time t; I(t) represents the drive current at time t; represents the slope efficiency at time t, representing the optical power gain corresponding to a unit current increment.

[0028] Based on the threshold current I th (t) of the test optical device and the corresponding time points, determine the aging rate coefficient and the time exponent n through the relational expression fitting of the threshold current and time, so as to obtain the statistical prediction model.

[0029] Use the Arrhenius degradation model to fit the aging rate of the optical device and abstract the relational expression of the threshold current and time:

[0030] ;

[0031] Among them, I th0 represents the initial threshold current; represents the aging rate coefficient; I th (t) represents the threshold current at time t; n represents the time exponent (0.5 ≤ n ≤ 1).

[0032] Step S12: Collect the initial threshold current I th0,p of the optical device to be compensated, and substitute it into the statistical prediction model to obtain the predicted threshold current I th,p (t) of the optical device to be compensated at time t.

[0033] Step S13: Collect the output optical power P out (t) and the drive current I(t) of the optical device to be compensated at time t. Based on the output optical power P out (t), the drive current I(t), and the predicted threshold current I th,p (t) at time t, calculate the slope efficiency at time t through the relationship between the output optical power and the drive current:

[0034] .

[0035] It is worth mentioning that during the operation of the optical device, as the working time increases, the optical device will gradually age. At the same drive current, the actual output optical power of the optical device gradually becomes smaller than the designed optical power (i.e., the target optical power).

[0036] Step S14: Based on the target optical power P target , the initial threshold current I th0,p , the output optical power P out (t) at time t, the predicted threshold current I th,p (t) at time t, and the slope efficiency at time t, calculate the theoretical compensation amount at time t:

[0037] ;

[0038] Among them, represents the theoretical compensation amount at time t; P target represents the target optical power.

[0039] In the whole Step S1, through the aging test of multiple test optical devices and the establishment of a statistical prediction model based on the aging test data, the threshold current of the optical device to be compensated at time t is accurately predicted, so as to accurately calculate the theoretical compensation amount of the drive current of the optical device to be compensated at time t, laying a foundation for the accurate calculation of the final fusion compensation amount.

[0040] Step S2: construct a real-time feedback model based on the step response test results of the test optical device, and use the real-time feedback model to calculate the feedback compensation amount of the drive current of the optical device to be compensated at time t.

[0041] The step S2 specifically includes the following steps:

[0042] Step S21: performing a step response experiment on the experimental optical device under different driving currents, determining and constructing a real-time feedback model based on the proportional gain and the integral gain.

[0043] It is worth mentioning that, in this embodiment, once the optical device starts to work, the optical device begins to age gradually, and the working time of the optical device is also the aging time.

[0044] The step S21 specifically includes the following steps:

[0045] Firstly, four aging time nodes are set, and step response experiments of the four aging time nodes are performed under different driving currents to obtain four corresponding sets of critical gains and critical periods.

[0046] Among them, the four aging time nodes are 0h, 2000h, 5000h and 8000h respectively.

[0047] Then, based on the four groups of critical gains and critical periods corresponding to the four aging time nodes, four groups of proportional gains and integral gains are calculated through the Ziegler-Nicholas empirical formula.

[0048] Specifically, the step response experiment of the experimental optical device with an aging time of 0h under different driving currents is introduced as an example. Set the driving current I to 40mA and the target optical power P target is 2.5mW, initial K p =0.1 (to ensure a smooth adjustment process), K i =0 (at this time, it is only adjusted by proportional control); collect the output optical power P out (t) and calculate the optical power error ,according to Adjust the drive current to (The closed-loop regulation of optical power is achieved through proportional control, so that the actual output optical power gradually approaches the target optical power.) Then, the target optical power P target Increase to 2.8mW (by artificially introducing a step input to force the system to exhibit critical oscillation characteristics during the adjustment process), and slowly increase K in steps of 0.1 p Observe the optical power curve of the oscilloscope; when there are at least 5 cycles of continuous equal-amplitude oscillation, record the K p , which is the critical gain K cr , read the time from the peak to the trough, which is the critical period Tcr Finally, a set of proportional gains is calculated according to the Ziegler-Nichols empirical formula. and integral gains . This set of proportional and integral gains is used as the proportional and integral gains corresponding to 0 - 2000 h. Similarly, a set of proportional and integral gains corresponding to 2000 - 5000 h, a set of proportional and integral gains corresponding to 5000 - 8000 h, and a set of proportional and integral gains corresponding to above 8000 h can be obtained.

[0049] Finally, based on the four sets of proportional and integral gains, a real-time feedback model is constructed.

[0050] For example, if the aging time of the optical device to be compensated is less than 2000 h, a set of proportional and integral gains corresponding to the interval of 0 - 2000 h is taken to construct the real-time feedback model.

[0051] Specifically, based on the target optical power P of the compensated optical device target and the output optical power p at time t out (t), the optical power error is calculated:

[0052] ;

[0053] where represents the optical power error at time t.

[0054] The derivative of the optical power error is taken to obtain relation one:

[0055] ;

[0056] The relation between the output optical power and the drive current is substituted into relation one to obtain relation two:

[0057] ;

[0058] Since the changes of the slope efficiency and the threshold current within the control period are extremely slow and can be approximately regarded as constants, relation two is simplified to obtain the error equation:

[0059] .

[0060] It can be seen from the error equation that when the optical power error approaches 0, the drive current approaches a constant, that is, the optical power error and the drive current satisfy the proportional-integral control condition. Therefore, based on the proportional gain, integral gain, and proportional-integral control expression corresponding to the aging time, a proportional-integral controller for the drive current is constructed:

[0061] ;

[0062] Based on the optical power error and the proportional-integral controller, a real-time feedback model is obtained:

[0063] ;

[0064] where represents the feedback compensation amount at time t.

[0065] Step S22: Input the target optical power of the optical device to be compensated and the output optical power at time t into the real-time feedback model to obtain the feedback compensation amount at time t.

[0066] In the entire Step S2, a step response test is performed on multiple optical devices, and a real-time feedback model is established based on the test results. At the same time, combined with the aging test of the optical device, the proportional gain and integral gain are set in multiple aging time intervals of the optical device, so that the feedback compensation amount of the optical device to be compensated at time t can be calculated more accurately, thereby accurately correcting the theoretical compensation amount obtained in Step S1, avoiding over-compensation, and greatly improving the accuracy of the drive current compensation.

[0067] Step S3: Based on the life-time inflection point of the optical device, a weight function is established; the theoretical compensation amount and the feedback compensation amount are weighted and fused through the weight function to obtain the final fusion compensation amount of the drive current of the optical device to be compensated at time t.

[0068] The specific steps of Step S3 are as follows:

[0069] Step S31: Based on the life-time inflection point of the optical device, a weight function is established.

[0070] The specific steps of Step S31 are as follows:

[0071] Set the initial values of the life-time inflection points, where the life-time inflection points include the first time inflection point t0 and the second time inflection point t1. Establish a weight function based on the initial values of the first time inflection point t0 and the second time inflection point t1 :

[0072] .

[0073] According to the analysis of a large amount of experimental data, the initial value of the first time inflection point t0 is preferably taken as 2000h, and the initial value of the second time inflection point t1 is preferably taken as 8000h.

[0074] Collect the actual threshold current I of the optical device to be compensated at time t th,r , and calculate the prediction error of the predicted threshold current compared with the actual threshold current at time t:

[0075] ;

[0076] Among them, represents the prediction error at time t; I th,r represents the actual threshold current at time t.

[0077] As time changes, the actual threshold current and the predicted threshold current will also change. Therefore, the prediction error will also change. Record the critical time point when the prediction error reaches 10%, and update the first time inflection point to the critical time point when the prediction error is 10%; record the critical time point when the prediction error reaches 20%, and update the second time inflection point to the critical time point when the prediction error is 20%.

[0078] Step S32: Establish a fusion adjustment function based on the weight function:

[0079] ;

[0080] Among them, represents the final fusion compensation amount at time t.

[0081] Step S33: Perform weighted fusion on the theoretical compensation amount and the feedback compensation amount through the fusion adjustment function to obtain the final fusion compensation amount at time t.

[0082] In the entire Step S3, a piecewise weight function is established according to different aging time intervals, and weighted fusion is performed on the theoretical compensation amount and the feedback compensation amount. The theoretical compensation amount can be accurately corrected according to the different aging degrees of the optical device to be compensated in different time periods, so as to obtain a final fusion compensation amount that better matches the aging degree of the optical device to be compensated at time t, and improve the compensation accuracy of the drive current of the optical device to be compensated.

[0083] Step S4: When the ratio of the slope efficiency at time t to the initial slope efficiency is less than 0.95 and the final fusion compensation amount is within the compensation boundary conditions, compensate the drive current of the optical device to be compensated at time t based on the final fusion compensation amount.

[0084] The specific steps of the said Step S4 include the following steps:

[0085] Step S41: Establish compensation boundary conditions based on the maximum allowable junction temperature of the optical device.

[0086] Based on the definition of thermodynamics, define the thermal resistance of the optical device:

[0087] , ;

[0088] Among them, R th represents the thermal resistance of the optical device; P h represents the heating power; represents the temperature rise; P outP represents the actual output power; V represents the device voltage; I represents the drive current.

[0089] Apply a fixed drive current to the test optical device, record the temperature rise curve, and simultaneously collect the actual output power and device voltage in real time, and then fit to obtain the thermal resistance of the optical device.

[0090] Compared with the aging cycle of the test optical device, the change in the drive current is extremely small. Therefore, the changes in slope efficiency, threshold current, and device voltage caused by the change in the drive current are ignored. Based on the law of conservation of energy, a formula for the increase in heating power is constructed:

[0091] ;

[0092] where V(t) represents the device voltage at time t; represents the increment of the compensated output power at time t.

[0093] Based on the formula for the increase in heating power, the compensated junction temperature at time t is obtained:

[0094] ;

[0095] where T j (t) represents the measured junction temperature before compensation at time t; represents the compensated junction temperature at time t.

[0096] Based on the compensated junction temperature and the maximum allowable junction temperature T M , a compensation boundary condition is established:

[0097] First, set the maximum allowable junction temperature T M , and constrain , to obtain the compensation boundary condition:

[0098] .

[0099] Step S42: Calculate the ratio of the slope efficiency of the optical device to be compensated at time t to the initial slope efficiency. If the ratio is less than 0.95, determine whether the final fusion compensation amount satisfies the compensation boundary condition; otherwise, directly output the drive current at time t.

[0100] Step S43: If the final fusion compensation amount satisfies the compensation boundary condition, compensate the drive current of the optical device to be compensated at time t based on the final fusion compensation amount, and output the compensated drive current; otherwise, directly output the drive current at time t.

[0101] Throughout step S4, a compensation boundary condition is established based on the maximum allowable junction temperature of the optical device to limit the final fusion compensation amount, which can avoid over-compensation causing the junction temperature of the optical device to be compensated to exceed the maximum allowable junction temperature, thereby accelerating the aging of the optical device to be compensated and further improving the compensation accuracy of the driving current of the optical device.

[0102] In this embodiment, the theoretical compensation amount of the driving current of the optical device to be compensated at time t is calculated through a statistical prediction model, and then the feedback compensation amount at time t is calculated through a real-time feedback model. Thus, the two are weighted and fused using a weight function to obtain the final fusion compensation amount, achieving the effect of using the feedback compensation amount to correct the theoretical compensation amount in real time, so as to avoid over-compensation of the driving current from accelerating the aging of the optical device and realizing precise and controllable compensation of the driving current. On this basis, by establishing a compensation boundary condition and finely limiting the compensation amount, the negative impact brought by over-compensation can be further avoided. Therefore, while extending the service life of the optical device, the present invention can correct the compensation amount of the driving current in real time according to real-time feedback, thereby precisely compensating the driving current. Thus, it can be seen that the present invention can ensure better use effects of the optical device while improving economic benefits.

[0103] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0104] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. An aging compensation method for an optical device, characterized in that, The method includes the following steps: S1. By collecting the aging experiment data of the test optical device, constructing a statistical prediction model, and using the statistical prediction model to calculate the theoretical compensation amount of the driving current of the optical device to be compensated at time t; S2. By the step response test results of the test optical device, constructing a real-time feedback model, and using the real-time feedback model to calculate the feedback compensation amount of the driving current of the optical device to be compensated at time t; S3. Based on the life time inflection point of the optical device, establishing a weight function; weighting and fusing the theoretical compensation amount and the feedback compensation amount through the weight function to obtain the final fusion compensation amount of the driving current of the optical device to be compensated at time t; S4. When the ratio of the slope efficiency at time t to the initial slope efficiency is less than 0.95 and the final fusion compensation amount is within the compensation boundary condition, compensating the driving current of the optical device to be compensated at time t based on the final fusion compensation amount.

2. The aging compensation method for the optical device according to claim 1, wherein The specific content of S1 includes: S11. Based on the aging test data of multiple test optical devices, through least squares fitting calculation, constructing a statistical prediction model; S12. Collect the initial threshold current I of the optical device to be compensated th0,p , and substitute it into the statistical prediction model to obtain the predicted threshold current I th,p (t) of the optical device to be compensated at time t; S13, collect the output optical power P out (t) and the drive current I(t) of the optical device to be compensated at time t, and based on the output optical power P out (t), the drive current I(t), and the predicted threshold current I th,p (t), calculate the slope efficiency at time t through the relationship between the output optical power and the drive current : ； S14, based on the target optical power P target , the initial threshold current I th0,p , the output optical power P out (t) at time t, the predicted threshold current I th,p (t) at time t, and the slope efficiency at time t , calculate the theoretical compensation amount at time t: ； Among them, represents the theoretical compensation amount at time t; P target represents the target optical power.

3. The aging compensation method for an optical device according to claim 2, wherein The specific content of S11 includes: S11-1, Collect the actual output power P of multiple test optical devices at different aging time points out and the actual drive current I as aging experiment data; S11-2. Based on the aging test data, calculate the threshold current I(t) at the corresponding time point by fitting the relationship between the output optical power and the drive current; the relationship between the output optical power and the drive current is: th (t); ； Among them, P out (t) represents the output optical power at time t; I(t) represents the drive current at time t; represents the slope efficiency at time t, representing the optical power gain corresponding to a unit current increment; S11-3, based on the threshold current I of the experimental optical device th (t) and the corresponding time points, perform fitting calculations through the relationship between the threshold current and time to determine the aging rate coefficient and the time exponent n, so as to obtain a statistical prediction model.

4. The aging compensation method for the optical device according to claim 1, characterized in that, The specific content of S2 includes: S21. Conducting step response experiments on the test optical device under different driving currents, determining and based on the proportional gain and integral gain, constructing a real-time feedback model; S22. Inputting the target optical power of the optical device to be compensated and the output optical power at time t into the real-time feedback model to obtain the feedback compensation amount at time t.

5. The aging compensation method for an optical device according to claim 4, characterized in that The specific content of S21 includes: S21-1. Setting four aging time nodes, and respectively conducting step response experiments at the four aging time nodes under different driving currents to obtain four corresponding sets of critical gains and critical periods; S21-2. Based on the four sets of critical gains and critical periods corresponding to the four aging time nodes respectively, calculating four sets of proportional gains and integral gains through the Ziegler-Nichols empirical formula; S21-3. Based on the four sets of proportional gains and integral gains, constructing a real-time feedback model.

6. The aging compensation method for the optical device according to claim 2, wherein The specific content of S3 includes: S31. Based on the life time inflection point of the optical device, establishing a weight function; S32. Based on the weight function, establishing a fusion adjustment function; S33. Weighting and fusing the theoretical compensation amount and the feedback compensation amount through the fusion adjustment function to obtain the final fusion compensation amount at time t.

7. The aging compensation method for the optical device according to claim 6, characterized in that, The specific content of S31 includes: S31-1, set the initial values of the lifetime inflection points, where the lifetime inflection points include the first inflection point t0 and the second inflection point t1; establish a weight function based on the initial values of the first inflection point t0 and the second inflection point t1 : ； S31-2, collect the actual threshold current I of the optical device to be compensated at time t th,r , and calculate the prediction error of the predicted threshold current compared to the actual threshold current at time t: ； Among them, represents the prediction error at time t; I th,r represents the actual threshold current at time t; S31-3. Recording the critical time point when the prediction error reaches 10%, and updating the first time inflection point to the critical time point when the prediction error is 10%; recording the critical time point when the prediction error reaches 20%, and updating the second time inflection point to the critical time point when the prediction error is 20%.

8. The aging compensation method for the optical device according to claim 2, wherein The specific content of S4 includes: S41. Based on the maximum allowable junction temperature of the optical device, establishing a compensation boundary condition; S42. Calculating the ratio of the slope efficiency of the optical device to be compensated at time t to the initial slope efficiency. If the ratio is less than 0.95, then determining whether the final fusion compensation amount meets the compensation boundary condition; otherwise, directly outputting the driving current at time t. S43. If the final fusion compensation amount meets the compensation boundary condition, compensate the drive current of the optical device to be compensated at time t based on the final fusion compensation amount, and output the compensated drive current; otherwise, directly output the drive current at time t.

9. The aging compensation method for the optical device according to claim 8, characterized in that The specific content of S41 includes: S41-1. Define the thermal resistance of the optical device based on the thermodynamic definition. S41-2. Ignore the changes in the slope efficiency, threshold current, and device voltage of the test optical device, and construct an incremental heating power formula based on the law of conservation of energy. S41-3. Obtain the compensated junction temperature at time t based on the incremental heating power formula. S41-4. Establish a compensation boundary condition based on the compensated junction temperature and the maximum allowable junction temperature.

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