Evaluation of optoelectronic components reliability for space applications: contribution of electro-optical characterization and modelling

In this work, the reliability of 980 nm pump laser diode and InGaAs photodiode modules has been estimated for space applications. The space environment is particularly harsh (vacuum, radiation, thermal and mechanical stresses) for these electro-optical devices, which were designed for long-haul submerged telecommunication applications. The main objective of this thesis is to provide a guideline for the space evaluation of optoelectronic devices, using characterization, physical analysis and modeling. Eight laser diodes were aged in vacuum (10^-7 mbar) during 5000 h, at 60 deg. C and 800 mA bias current. The hermeticity of four of them was voluntarily broken to simulate a long term vacuum exposition. Three of four non-hermetic devices failed during the ageing, because of COD (Catastrophic Optical Damage) whereas the electro-optical characteristics of hermetic devices remained unchanged. The MTBF of laser diodes operating in vacuum was estimated to 26 years, by means of modeling (electro-optics and pressure) and physical analyses (AFM, SEM, TEM, cathodoluminescence, ToF-SIMS). InGaAs photodiodes were irradiated by protons, with energies ranging from 30 to 190 MeV and fluences ranging from 5.10¹⁰ to 10¹² p/cm². The dark current increased by three decades after irradiation. The photodiode MTBF was then estimating to 15 years using dark current modeling. This study also permitted to show up almost new failure mechanisms (COD under vacuum, NIEL scaling errors in InGaAs, Bragg grating degradation under ionizing radiation and its effects on laser diode stabilization), which could contribute to the space evaluation of laser diodes and photodiodes for future missions. (author)