Test method for evaluating the life of a pump laser for subsea optical communication in the order of 100 milliwatts

Abstract

The present application relates to a kind of test method for evaluating the life of pump laser for subsea optical communication of hundreds of milliwatts, belongs to the technical field of pump laser for optical communication.The general idea of the present application is that, since the chip is the weak link that restricts the life of pump laser, the activation energy and current acceleration factor in the chip life model are approximately equal to the activation energy and current acceleration factor in the life model of module, so that the accelerated aging life test of chip under multiple groups of different conditions is used to replace the accelerated aging test of multiple groups of modules, to obtain the activation energy and current acceleration factor in the life model, which greatly reduces the test difficulty and cost.In addition, the method of simultaneous acceleration under multiple conditions is used in the life model, such as temperature acceleration and current acceleration are carried out at the same time, and the number of samples is increased, the test time can be reduced from 8000h to 5000h, to 4000h to 2000h.The test method can greatly save cost and time, and provide a way for more convenient and rapid evaluation of product life in the stages of product pre-research, initial sample, etc.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pump lasers for optical communication, and particularly relates to a test method for evaluating the service life of a pump laser for optical submarine communication with a power of hundreds of milliwatts. BACKGROUND

[0002] Optical submarine communication has replaced submarine electric communication to a large extent due to its advantages such as large capacity, low loss, no interference from electromagnetic waves, and safety and reliability, and has become an important means of contemporary international communication, and has great significance for the development of national security and military defense. An underwater optical repeater is the most important device of a repeater cable system, which is laid on the seabed with a depth of several hundred meters to eight thousand meters. Under such conditions, once maintenance is required, the cost is extremely high, so high requirements are put forward for the reliability of the device, and the service life of the optical repeater should be no less than 25 years (T / GD ACERCU 0002-2019 Technical Requirements for Optical Submarine Repeaters). A pump laser with a power of hundreds of milliwatts, as a key optical device in the repeater device, should also have a service life of no less than 25 years. In the past, products that meet this technical index mainly relied on imports, and the suppliers were mainly Lumentum and II-VI of the United States. With the rapid development of semiconductor pump laser research and development projects and application markets in China, the technology of pump lasers with a power of hundreds of milliwatts for optical communication is gradually mature. According to research, many domestic units have initially developed the ability to meet the requirements of high power and high reliability (Literature: Liu Jun, Li Bozhong, Chen Fang, etc. 400mW 980nm Pump Laser Design [J]. Optical Communication Research, 2023 (2): 63-68), but there is no unified and standard service life test method in China at present. In reference to similar service life evaluation methods, it is found that the evaluation method is complex and time-consuming, which is not conducive to the rapid evaluation of the service life of products in the research stage.

[0003] Imported products are based on standards (Telcordia GR-468-CORE Generic reliability assurance requirements for optoelectronics devices used in telecommunication equipment and MIL-STD-883E Department of defense test method standard microcircuits), and an accelerated service life aging test is directly performed on the laser module. This test requires a large number of test boxes that can meet the requirements of specific packaging sizes and power supply, and the operation is not convenient. A large number of products are required for the test, which is time-consuming and costly.

[0004] A domestically published patent, "Lifetime Assessment Method and Assessment System for High-Power Semiconductor Laser Beam Combining Module" (application number 202211680976.9, publication date 2023.05.26), has an acceleration factor that only uses temperature acceleration, resulting in a relatively small acceleration coefficient and a long required testing time.

[0005] Therefore, it is necessary to propose a more effective and convenient experimental method for evaluating the lifetime of pump lasers used in submarine optical communication at the 100-milliwatt level. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] The technical problem to be solved by this invention is: how to propose a more effective and convenient test method for evaluating the lifetime of pump lasers used in submarine optical communication at the milliwatt level.

[0008] (II) Technical Solution

[0009] To address the aforementioned technical problems, this invention provides an experimental method for lifetime assessment of a pump laser used in submarine optical communication at the milliwatt level. This method involves conducting multiple accelerated aging tests under different conditions on the pump laser module chip to obtain the activation energy and current acceleration coefficient related to the failure mechanism of the estimated chip lifetime. The accelerated aging tests are conducted under various acceleration conditions with different currents and temperatures. Since pump laser failure is temperature-dependent, the failure rate is calculated using the Arrhenius relation.

[0010]

[0011] Where λ0 represents the failure rate under rated conditions, and E a It is the activation energy of the temperature-accelerated failure mechanism, K. B is Boltzmann constant; T is the junction temperature of the chip, I is the current, and the subscripts ag and op represent the accelerated aging life test level and the rated operating level, respectively.

[0012] In the accelerated lifetime model, λ0, E a m are parameters, I op K B T op For a defined constant, I ag T ag I is the independent variable, and λ is the dependent variable; five sets of independent variables I were obtained using multiple accelerated aging tests under different conditions. ag T ag And the dependent variable λ, substituting into equation (1) yields a system of equations, and λ0 and E are obtained at a certain confidence level through maximum likelihood estimation fitting. a m (confidence level is often taken as ≥60%); activation energy E in the lifetime model of the pump laser module.a and m is the activation energy E in the lifetime model of the chip a and m, i.e. the lifetime model of the pump laser module is:

[0013]

[0014] At the same time of the chip multi-condition accelerated aging test, a group of accelerated aging lifetime tests of the pump laser module are carried out; in formula (3), λ is the failure rate of the accelerated lifetime condition, χ is the confidence, N is the total number of devices, t i is the accelerated lifetime test duration of the i-th device; the current, temperature of the accelerated aging lifetime test of the pump laser module, and the failure rate obtained under the accelerated aging test condition are substituted into formula (2) to obtain the failure rate of the pump laser module, and whether the lifetime of the pump laser module meets the index is judged according to the failure rate of the pump laser module.

[0015] Preferably, if the failure rate is within 100 FIT, it is considered that the lifetime of the pump laser module meets the 25-year index; if the failure rate is greater than 100 FIT, it is considered that the lifetime of the pump laser module is less than the 25-year index.

[0016] Preferably, the chip is a chip from different wafers.

[0017] Preferably, when a plurality of groups of accelerated aging tests of the chip are carried out under different temperatures and currents, the temperature is set to 95℃±5℃, 80℃±5℃ and 65℃±5℃ respectively under the condition that the current is 1.5A±0.05A, and the current is set to 1.7A±0.05A, 1.5A±0.05A and 1.3A±0.05A respectively under the condition that the temperature is 80℃, and a total of 5 groups of tests are carried out.

[0018] Preferably, when a group of accelerated aging lifetime tests of the module are carried out synchronously, a group of packaged pump laser modules are selected and placed in an accelerated aging test box, the current is set to 1.5A±0.05A and the temperature is set to 95℃±5℃, and the failure of each module in the aging process is monitored.

[0019] The application also provides a system for implementing the method.

[0020] The application also provides a method for using the system.

[0021] (Three) beneficial effects

[0022] The general idea of the present application is that, since the chip is the weak link that restricts the life of the pump laser, the activation energy and the current acceleration factor in the chip life model are approximately equal to the activation energy and the current acceleration factor in the module life model, so that the accelerated aging life test of the chip under multiple sets of different conditions is used to replace the accelerated aging test of multiple sets of modules to obtain the activation energy and the current acceleration factor in the life model, which greatly reduces the test difficulty and cost. In addition, multiple conditions are accelerated simultaneously in the life model, such as temperature acceleration and current acceleration, and the number of samples is increased, and the test time can be reduced from 8000h to 5000h to 4000h to 2000h.

[0023] The test method can greatly save cost and time, and provide a method for more convenient and rapid evaluation of the life of products in the pre-research and initial sample stages. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The method flowchart of the embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, content and advantages of the present application clearer, the specific embodiments of the present application are described in further detail below in combination with the drawings and examples.

[0026] The pump laser mainly consists of a chip, a heat sink, a shell, metal pins, an output fiber and the like, wherein the chip is the most important core component and is also the key to restricting the life of the pump laser. The test method for evaluating the life of the pump laser for submarine optical communication provided by the present application is to obtain a life model through chip-level accelerated aging test. Compared with obtaining a life model through module-level accelerated aging test, the method greatly reduces the difficulty in operation and also greatly reduces the test cost without the need for a large number of packaged modules. On the other hand, multiple accelerations are selected in the acceleration model: temperature acceleration, current acceleration and the like. Compared with a single acceleration model with only temperature acceleration or current acceleration, the acceleration factor is increased by several times, which greatly reduces the test time.

[0027] The present application uses the chip to perform accelerated aging tests under multiple sets of different conditions (high temperature, high current and the like) to obtain the failure mechanism related activation energy and the current acceleration coefficient for estimating the life of the chip. The accelerated aging test should select multiple different current and temperature acceleration conditions.

[0028] The failure of the pump laser belongs to temperature-dependent failure, and the Arrhenius relationship is used to calculate the failure rate:

[0029]

[0030] wherein λ0 is the failure rate under rated conditions, E a is the activation energy of the temperature acceleration failure mechanism, and KB is Boltzmann constant (8.618*10-5eV / K); T is the junction temperature of the chip (unit: K), I is the current, P is the power, and the subscripts ag and op represent the accelerated aging life test level and the rated working level, respectively.

[0031] In the accelerated life model, λ0, E a , m are parameters, I op , K B , T op are determined constants, I ag , T ag are independent variables, and λ is a dependent variable. Accelerated aging under multiple sets of different conditions can obtain five sets of independent variables (Iag, Tag) and dependent variables (λ), which are brought into equation (1) to obtain an equation group, and λ0, E a , m (the confidence level is usually ≥ 60%) are obtained by maximum likelihood estimation fitting. As a weak link that restricts the life of the pump laser, the chip, the activation energy E a and m in the life model of the module are approximately the activation energy E a and m in the life model of the chip.

[0032] That is, the life model of the module is:

[0033]

[0034] At the same time of the accelerated aging test of the chip under multiple conditions, a set of accelerated aging life tests of the module are simultaneously carried out. In formula (3), λ is the failure rate under the accelerated life condition, χ is the confidence level (which can be obtained by looking up a table), N is the total number of devices, and t i is the accelerated life test time length of the i-th device (unit: hour). The current and temperature set in the accelerated aging life test of the module and the failure rate obtained under the accelerated aging test condition are substituted into formula (2), and thus the failure rate of the module can be obtained.

[0035] According to actual requirements, if the failure rate is within 100 FIT, it is considered that the life of the module meets 25 years. If the failure rate is greater than 100 FIT, it is considered that the life of the module is less than 25 years.

[0036] Please refer to the accompanying drawings Figure 1 and specific embodiments provided by the present application for a test method for evaluating the life of a pump laser for a submarine optical communication of a hundred milliwatt order, which specifically includes the following steps.

[0037] Step 1: providing a chip to be tested. In the case where conditions permit, chips from different wafers are randomly selected as much as possible to avoid test errors caused by group clustering;

[0038] Step 2:

[0039] Step 2-1: Set different temperature, current and other conditions to carry out accelerated aging test of multiple chips. For example, under the condition of current 1.5A±0.05A, the temperature is set to 95℃±5℃, 80℃±5℃, 65℃±5℃ respectively, and under the condition of temperature 80℃, the current is set to 1.7A±0.05A, 1.5A±0.05A, 1.3A±0.05A respectively, a total of 5 groups of tests;

[0040] Step 2-2: Synchronously carry out accelerated aging life test of a group of modules. For example, select a group of packaged pump laser modules, place them in the accelerated aging test box, set the current to 1.5A±0.05A and the temperature to 95℃±5℃, and monitor the failure of each module during the aging process;

[0041] Step 3: Obtain the activation energy and acceleration factor of the chip according to the accelerated aging test data of the chip. Multiple groups of accelerated aging under different conditions can obtain multiple independent variables (Iag, Tag) and dependent variables (λ), which are brought into equation (1) to obtain equation group, and λ0, E a , m (the confidence level is usually ≥60%) are obtained by maximum likelihood estimation fitting under a certain confidence level;

[0042] Step 4: Obtain the activation energy and acceleration factor of the chip according to the accelerated aging test data of the chip, i.e. obtain the activation energy and acceleration factor of the module;

[0043] Step 5: Obtain the life model of the module;

[0044] Step 6: Substitute the accelerated aging life test conditions and test results of the module into the life model of the module, i.e. formulas (2), (3), to obtain the failure rate of the module;

[0045] Step 7: Determine whether the failure rate of the module is within 100 FIT. If the failure rate of the module is within 100 FIT, execute step 8; if the failure rate of the module is not within 100 FIT, execute step 9;

[0046] Step 8: Determine that the life of the module meets the 25-year index;

[0047] Step 9: Determine that the life of the module does not meet the 25-year index.

[0048] The above only describes the preferred embodiments of the present application. It should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A test method for evaluating the lifetime of a pump laser for a subsea optical communication system in the order of 100 mW, characterized by, In the method, a chip of a pump laser module is used to carry out a plurality of groups of accelerated aging tests under different conditions to obtain failure mechanism related activation energy and current acceleration coefficient of estimated chip life; wherein the accelerated aging tests are selected under a plurality of different current and temperature acceleration conditions; the pump laser failure belongs to temperature dependent failure, and Arrhenius relationship is used to calculate the failure rate: where λ0is the failure rate under rated conditions, E a is the activation energy of the temperature-accelerated failure mechanism, K B is the Boltzmann constant, m is the acceleration factor; T is the junction temperature of the chip, I is the current, and the subscripts ag and op represent the accelerated aging life test level and the rated operating level, respectively; In the accelerated lifetime model, λ0, E a m are parameters, I op K B T op For a defined constant, I ag T ag I is the independent variable, and λ is the dependent variable; five sets of independent variables I were obtained using multiple accelerated aging tests under different conditions. ag T ag And the dependent variable λ, substituting into equation (1) yields a system of equations, and λ0 and E are obtained at a certain confidence level through maximum likelihood estimation fitting. a The activation energy E in the lifetime model of the pump laser module; m; a And m is approximated as the activation energy E in the chip lifetime model. a The lifetime model for m, i.e., the pump laser module, is as follows: At the same time of the chip multi-condition accelerated aging test, a group of pump laser module accelerated aging life test is carried out; in formula (3), λ is the failure rate of accelerated life condition, χ is the confidence, N is the total number of devices, t i is the accelerated life test duration of the i th device; the current, temperature of the pump laser module accelerated aging life test, and the failure rate obtained under the accelerated aging test condition are substituted into formula (2) to obtain the failure rate of the pump laser module, and whether the life of the pump laser module meets the index is judged according to the failure rate of the pump laser module.

2. The method of claim 1, wherein, If the failure rate is within 100 FIT, it is considered that the life of the pump laser module meets the 25-year index; if the failure rate is greater than 100 FIT, it is considered that the life of the pump laser module is less than the 25-year index.

3. The method of claim 1, wherein, The chip is from different wafers.

4. The method of claim 1, wherein, When a plurality of groups of accelerated aging tests of the chips are carried out under different temperatures and currents, under the condition that the current is 1.5A±0.05A, the temperature is set to 95℃±5℃, 80℃±5℃ and 65℃±5℃ respectively, under the condition that the temperature is 80℃, the current is set to 1.7A±0.05A, 1.5A±0.05A and 1.3A±0.05A respectively, and a total of 5 groups of tests are carried out.

5. The method of claim 4, wherein, When a group of accelerated aging life tests of the modules are carried out synchronously, a group of packaged pump laser modules are placed in an accelerated aging test box, the current is set to 1.5A±0.05A and the temperature is set to 95℃±5℃, and the failure of each module in the aging process is monitored.

6. The method of claim 1, wherein, The pump laser includes a chip, a heat sink, a shell, metal pins and an output fiber.

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