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1.INTRODUCTIONThe MetOp-SG satellite program is an EUMETSAT/ESA cooperation with the objective to obtain long-term collection of remotely sensed data of uniform quality for meteorology and climate monitoring state analysis and forecast. A series of three satellite pairs (MetOp-SG-A and MetOp-SG-B) are to be launched, ensuring continuity of data beyond 2045. The Infrared Atmospheric Sounding Interferometer New Generation (IASI-NG) is a key payload element of the second generation of European meteorological polar-orbit satellites METOP-SG-A, dedicated to operational meteorology, oceanography, atmospheric chemistry, and climate monitoring. The LASE unit was presented[1] at ICSO 2018, this paper focus on the qualification of the LDM. The core component in a laser system is the Laser Diode Module (LDM). While laser sources in the telecommunication wavelength range near 1550 nm are easily available for terrestrial use as COTS, their suitability for space applications need to be assessed. For the LASE unit, a Furukawa Fitel FRL15DCWD-A82-W19430-B LDM was chosen, and a Lot Acceptance Test (LAT) was performed. This paper is divided into a description of the qualification campaign and results in chapter 2 and summary and conclusions in chapter 3. 2.LDM QUALIFICATIONThe qualification campaign test flow is shown in Figure 2-1. The LAT was divided into sub-groups, mechanical, thermal, endurance and radiation tests, and constructional analysis. Constructional analysis was also performed on some of the devices after environmental tests. The different tests are presented in separate sections. The Furukawa Fitel FRL15DCWD-A82-W19430-B[2] laser diode is rated for use at 40 mW, a picture is shown in Figure 2-2. To account for derating, the LDMs were qualified at 28 mW. Furukawa qualify their lasers in accordance with standard Telcordia GR-468-CORE. For the space qualification, all tests were performed by Alter Technology in Spain. A total of 71 LDMs were screened, and 43 of those were included in the LAT. The Electro-optic characterization consisted of measurements of the following parameters and their drifts:
2.1ScreeningPrior to the tests, all devices were screened, including burn-in and x-ray inspection of the laser diodes. The screening flow is shown in Figure 2-3. Based on the electro-optical measurements, 7 of the 71 LDMs had anomalies, including too high drifts, operating temperature slightly outside specifications and other minor discrepancies. Where the anomalies had no impact on the test results, the LDMs were included in the LAT. A representative image from the X-ray inspection is shown in Figure 2-4. 2.2Mechanical tests7 LDMs were mechanically tested, see test flow in Figure 2-1. The test levels for the mechanical tests are shown in Table 2-1 - Table 2-3. The test setup is shown in Figure 2-5. Resonance search and leak tests were performed, which showed no anomalies in the measurements. The leak rates were all below 1E-9 atm·cc/ss. Table 2-1Random vibration levels
Table 2-2Sine vibration levels
Table 2-3Shock levels
2.3Thermal testsThermal tests were performed on 10 LDMs, in accordance with the test flow shown in Figure 2-1. 5 of the LDMs were also exposed to a moisture test. Thermal cycles were performed according MIL-STD-883 TM1010 and customer requirements. A picture of the test setup is shown in Figure 2-6. The following test conditions were applied:
Moisture test conditions: All LDMs passed the tests within required drifts. 2.4Endurance testsThe endurance test flow is shown in Figure 2-1. A total of 20 lasers were included in this group, 5 were tested for non-operating high temperature storage test, and the other 15 were tested for 2000h in operating conditions. 10 of the 15 LDMs were tested for an additional 1000h. The following test conditions were used for the Steady State Life Test (Endurance) test: The following test conditions were used for the High Temperature Storage test:
Due to a non-conformance in the test equipment, 1 LDM did not complete the tests. The root cause was found to be a TEC controller that failed after 580h operation. No LDMs failed due to the endurance test level or duration. 2.5Constructional AnalysisThe constructional analysis test flow is shown in. It was performed on 3 designated LDMs, and in addition 2 LDMs from each of the following groups were included: Endurance, Thermal and Mechanical. A minor defect was found on an LDM during SEM inspection, see Figure 2-8. A small piece of the top metallization remained on the laser chip after die cutting. This LDM was from the mechanical testing group. The metal had survived the mechanical tests, and also too small to cause any short-circuits. The anomaly was not cause for rejection. Figure 2-8SEM picture of laser chip, showing small piece of top metallization remaining after die cutting.  External visual inspection: No anomalies detected, all samples passed the test. Marking Test: Good marking legibility after the test, all samples passed the test. PIND Test: No loose particles were detected, all samples passed the test. Terminal Strength: No damage was observed in the terminals, all samples passed the test. Seal-Test: All samples passed the test (leak rate < 1E-9 atm.cc/s). 2.6Radiation tests3 LDMs were radiation tested, the test flow is shown in Figure 2-1. Radiation tests were performed using ESCC22900 as a guideline onto a reduced subset of 3 samples. Total Ionizing Dose test was performed according the following test conditions:
Displacement Damage test (Protons radiation) was performed according the following test conditions:
Figure 2-10The drift in optical power due to radiation environment. The measurements were corrected to account for variation in the test setup. Reference LDM 67552A01, which was not radiation tested, was used for the normalization.  No issues were detected during test. 4.ACKNOWLEDGEMENTSThe development of the LASE has been performed in the frame of Contract No 4500504806 between Airbus Defence and Space SAS and Kongsberg Defence & Aerospace AS. Thanks to CNES, Airbus, Alter and Furukawa for their contributions and feedback to this work. All images from the test setups are courtesy of Alter Technology. REFERENCESLierstuen, L., Thomassen, S. F., Saether, E. T., Johnsen S.; Hagaas B.; Brecht C.; Raknerud R., Lien Y., Miljeteig I., Frøen E. and Lockey T.,
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