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Dark current and associated random telegraph signals are studied in short-wave infrared image sensors. The effects of space radiation on these parameters are analyzed and modeled to understand the degradation in this indium–gallium–arsenide (InGaA)-based technology. Multiple proton tests were performed to cover the space mission range of radiation dose. Comparison with existing data and damage factors is provided and highlights the behavior of such technology against radiation doses.

International audience

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data. In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds.

The SuperCam instrument was selected by NASA in July 2014 and has been implemented on the Mars 2020 Perseverance rover. This instrumental suite gathers four different remote-sensing techniques including a very compact Infrared Spectrometer (IRS). For several reasons of costs and planning and after a risk mitigation phase, the use of full commercial-off-the-shelf photodiodes from TELEDYNE JUDSON J19 Series as detector for the IRS was decided. This paper describes the procurement, evaluation, and qualification philosophy of these photodiodes, providing information on the subsystems of the SuperCam instrument and the description of these photodiodes. Critical and fragile parts of the photodiode as the thermo electric cooler, have been particularly studied. In conclusion, the component was space qualified using the original use of the particle impact noise detection test applied for a mechanical screening purpose, with correlation between performance and fine leak, screening and the lot acceptance test processes.

International audience; Space system undergo particularly hard natural radiation environment, but can also potentially be subject to the radiations injected in low earth orbit by the explosion of a nuclear weapons. The increasing use of optoelectronic components in space systems makes the risk assessment regarding the radiation effects of an increasing interest. This paper presents recent results about the degradation of optoelectronic devices in term of atomic displacements. This paper Most of this work has been developed under the EDA contract JIP-ICET2 A-1341-RT-GP within the CapTech Technologies for Components and Modules’ (TCM) in EDA.

Photovoltaic cells are detrimentally impacted by exposure to ionizing radiation, a consideration of particular significance for applications in outer space. In this paper, we demonstrate that vertical epitaxial heterostructure architecture (VEHSA) laser power converters are particularly resilient toward radiation-induced degradation; in particular, we observed reductions in efficiency of 1.9% and 6.4% for 5- and 20-junction monolithic devices, respectively, at near 3 W of input power ( $V_{\textrm {oc}}$ of 5.78 and 23.32 V and peak response near 850 nm). This contrasts markedly with the 16.9% and 25.4% reductions in efficiency for the same 5- and 20-junction devices when using a detuned source at 808 nm, which we attribute to a reduction in nonradiative recombination lifetimes leading to a suppression of radiative recombination driven photon recycling.

This paper, “A new concept of flared amplifier for high brightness source," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

International audience; In this paper, a compendium of InGaAs photodiode irradiation test results is presented. These photodiodes were irradiated either with γ-rays, protons, neutrons, electrons, pions, alpha particles, or carbon ions of various energies. The displacement damage dose formalism was found to be effective in describing the radiation-induced dark current increase of any of the studied InGaAs photodiodes. The exploitation of capacitancebias voltage and current-bias voltage measurements also allows us to deduce a damage factor that can be used to assess the radiation-induced dark current in a great number of radiation environments.

Silicon transistor test vehicles used in infrared detectors were exposed to total dose at cryogenic temperatures. We present the degradation of the leakage current and threshold voltage of different transistor topologies at different dose rates and temperatures. The results show that the degradation occurs in the lateral parts of the transistors. Moreover, a different degradation was observed at 83 and 108 K. The higher temperature corresponds to the higher degradation; this can be explained by a more efficient hole transport process at these temperature. Measurements during the warming process of the devices show that a competition exists between the hole transport and their annealing, suggesting that a worst case of degradation could be found between nitrogen and room temperature.

Radiation is a major issue for satellite development, especially when using detectors, either for the mission itself, or for platform sensors. This paper will give CNES experience in the effects of radiations on detector and mission performances. Data from several satellites is presented (Earth observation, Astronomy, star trackers). We will make comparison between this data, to try to determine common behaviours. We will finish by describing the mitigation techniques against radiation effects.

The dark current spectroscopy is tested on twenty CMOS image sensors irradiated with protons, neutrons and various ions at different energies. The aim of this work is to differentiate the effect of coulomb and nuclear interactions on the radiation-induced dark current distribution and to identify the main radiation-induced defects responsible for the dark current increase for each type of interaction. For low-energy protons and low-energy light ions (which produce well-separated low energy coulomb interactions), we find that most of the pixels belong to a quantized dark current spectrum at low dark current. In these pixels, the dark current increase seems mainly dominated by specific point defects such as the divacancy and the vacancy-phosphorus complex. Thus, these simple defects seem to form when the displacement damage is rather low and sparse. On the contrary, for nuclear interactions (with neutrons or high-energy protons) producing high coulomb NIEL silicon PKAs or for low energy heavy ions (also having high coulomb NIEL), the DCS spectrum is not visible and all the pixels belong to an exponential hot pixel tail which extends to very high dark current. In these pixels, the dark current increase is mainly dominated by defects with close-to-midgap energy levels. These defects seem more complex than point defects because they can have many different generation rates (explaining the smooth hot pixel tail) and because they tend to form when the displacement damage is high and dense.

This paper aims to propose a new approach to model the Dark Current Random Telegraph Signal (DC-RTS) maximum transition distribution in irradiated CMOS Image Sensors (CIS). Based on some outcomes of the Extreme Value Theory (EVT), it can be used to predict this distribution at the end of a given space mission. An example of application of this methodology is presented in detail.

The radiation tolerance of a 0.18 μm technology CMOS commercial image sensor has been evaluated with Co60 and proton irradiations. The effects of protons on the hot pixels and dynamic bias and duty cycle conditions during gamma irradiations are studied.

The dark current random telegraph signal (RTS) behavior has been studied in a five-transistor-per-pixel (5T) pinned photodiode 0.18-μm COTS active pixel sensor (APS). Several devices, irradiated using protons and gamma rays, have been studied in order to assess the ionizing and displacement damage effects. The influence of the proton energy, fluence, ionizing dose and applied bias during irradiation on the number of RTS pixels, the number of discrete levels, maximum transition amplitude, and mean switching time constants is investigated.

International audience; The dark current produced by neutron irradiation in CMOS Image Sensors (CIS) is investigated. Several CIS with different photodiode types and pixel pitches are irradiated with various neutron energies and fluences to study the influence of each of these optical detector and irradiation parameters on the dark current distribution. An empirical model is tested on the experimental data and validated on all the irradiated optical imagers. This model is able to describe all the presented dark current distributions with no parameter variation for neutron energies of 14 MeV or higher, regardless of the optical detector and irradiation characteristics. For energies below 1 MeV, it is shown that a single parameter has to be adjusted because of the lower mean damage energy per nuclear interaction. This model and these conclusions can be transposed to any silicon based solid-state optical imagers such as CIS or Charged Coupled Devices (CCD). This work can also be used when designing an optical imager instrument, to anticipate the dark current increase or to choose a mitigation technique.

In our previous works we have demonstrated that Design of Experiments (DoE) is an innovative methodology defining optimized irradiation test plan and particularly valuable for the space qualification of silicon photodetectors. In particular, it provided us with the degradation model of photocurrent, darkness current, and spectral responsivity of silicon based phototransistors arrays with respect to the Total Ionizing Dose (TID) and to the Displacement Damage Dose (DDD), over a wide range of space-mission profiles. In this paper, we will summarize at first main results obtained thanks to the DoE methodology. Then we present how we can easily obtain, by exploiting DoE collected data, End-of-Life predictions of such devices with a reduced number of experiments, with a small batch of devices, and in relatively short time.

Dark current evolution in Charge Coupled Devices (CCD) is experimentally studied with Co-60 and proton irradiations. Linear CCDs are irradiated in various static and dynamic bias conditions. Annealing effects are discussed and on-ground data are compared to in-flight data. Presented results on ionization-induced dark current increase in CCDs have demonstrated the impact of the sensor operational conditions and dose rate, revealing an ELDRS-like effect.

This paper presents the analysis of the CoRoT CCDs dark current degradation measured during more than 2.5 years in orbit. Starting from on-ground irradiation results obtained during the space qualification of the detectors, a model is proposed to calculate the in-orbit pixel dark current distribution (including the hot pixels one). The modeling results are found to be in good agreement with the in-flight data. We therefore use this model to extrapolate the evolution of the dark signal distribution beyond 2.5 years. This is of primary interest in the context of a mission duration extension to 6 years proposed for the CoRoT mission.

A Design Of Experiments (DOE) methodology was suggested to define an optimized irradiation test plan. In this paper, the proposed test plan was used to model the degradation of the main performances (photo and dark current) of silicon based phototransistors arrays with respect to the Total Ionizing Dose (TID) and to the Displacement Damage Dose (DDD), over a wide range of space-kind environments. The expected performance degradation after an 18-year Low Earth Orbit (LEO) mission was calculated using this model. End-Of-Life (EOL) prediction results were compared to experimental ones obtained on devices irradiated with a proton beam degrader that simulates the 18 year LEO environment. The excellent agreement found between theoretical and experimental data makes this methodology particularly valuable for the space qualification of such devices.

This paper presents the CNES analysis of CCD dark current degradation in orbit. For the first time, data coming from several detectors in orbit have been collected and congregated to extract general trends about in-flight detector behaviours. The in-orbit degradation is therefore compared to the on-ground prediction for each detector. This work has been done in collaboration with the CNES detection subsystem office, the CNES image quality office and the CNES components & environment effects office.

We present and compare different experimental methods used to determine defect introduction rates in materials constituting trijunction solar cells. Most of the experimental methods correlates together and with an analytical modeling. Defect introduction rates values in GaInP and GaAs are presented over a wide range of NIELs; this result seems intrinsic to these two materials.

We report on a novel method to measure radiation induced non radiative carrier lifetime modifications in laser diodes. This method is based on the conjugation of theoretical gain calculation, experimental gain measurements, and threshold variation measurements. We show that lifetime variations measured that way are in good agreement with those measured using time resolved photoluminescence (TRPL), and that the methodology can be applied to annealed samples, whose carrier lifetime cannot be otherwise measured.

In this paper, the thermal characteristics of packaged infrared double-heterostructure light emitting diode (DH-LED), used in space applications, are measured under conditions that reproduce space environments. The characterisation uses spontaneous optical spectrum characteristics, current–voltage curves and optical power measured under a primary vacuum (

852-nm emitting Al-free laser diodes and layers constituting the device are irradiated with 1-MeV electrons at fluences ranging from 1014 up to 1016e-/cm2. Layers corresponding to the laser diodes materials were characterised using photoluminescence and time resolved photoluminescence. Laser diodes L-I-V characteristics were measured in pulsed and continuous regime.

A silicon CCD imager has been irradiated with 10 MeV protons and measurements focused on random telegraph signal (RTS). A variance detection method is applied for quantifying the number of RTS after irradiation and through isochronal annealing. The observed behavior is analyzed and corresponds to the annealing of phosphorus-vacancies.

The hazards and vulnerability concepts are introduced after a brief review of the definition of risk. Hazards are essentially associated with any natural phenomenon investigated, while vulnerability is primarily a socioeconomic parameter influenced by other drivers of change such as demography. The risk concept derives from these two parameters. Given that there is no such thing as a zero risk situation, it is essential to introduce the idea of an acceptable level of risk which must be determined through a participatory process set in motion by society. Knowledge regarding these two risk components is dependent on the methods used to assess them and associated levels of uncertainty. The impact of climate change on hazards is hard to quantify because, under a constant climate, it is generally an order of magnitude below the natural existing uncertainty. Conversely, vulnerability is not well understood and few rigorous methods are available to quantify this factor. Clarifying hazards thus may seem to enhance the risk assessment but this is illusory since the less understood vulnerability factor is overlooked, which may lead to too much attention being focused on the hazards factor to the detriment of vulnerability management. This may also apply to other climate risks such as drought, although flooding risk is better understood. These considerations may be useful for the agricultural community which, besides its production function, could offer society other services of territorial scope, encompassing different areas, while in return benefitting from support measures that would make the risks more acceptable.

Dark Current Spectroscopy of radiation-induced defects is tested for the first time in CMOS Image Sensors. Several dark current peaks are observed and their evolution with fluence, particle energy and temperature is studied.

Dark Current Spectroscopy (DCS) is tested for the first time on irradiated Pinned PhohoDiode (PPD) CMOS Image sensors (CIS) to detect and identify radiation-induced silicon bulk defects in the depleted volume of the pixels. Two different CIS are tested: a 5MP Commercial-Off-The-Shelf (COTS) CIS from OmniVision (OV5647) and a 256x256 pixels custom CIS. These CISs are irradiated with alpha particles at various fluences and two different particle energies are tested on the custom CIS (4 MeV and < 500 keV). Several types of defects are detected in both CIS (up to five defects in the custom CIS). The dark current is measured at various temperatures to extract the activation energy and deduce the energy levels of the defects. The defect formation rate per unit fluence is calculated. In the custom CIS, the annealing behavior of the defects is also studied by performing an isochronal annealing. Two different defects are identified: the divacancy and the vacancy-phosphorus. This work proves that the DCS technique can be used on irradiated CIS to detect and identify radiation-induced defects in silicon.

International audience; Pump laser diodes emitting at 980 nm are typically used in distribution network transmission systems and are now implemented in space missions for intra-satellite communication links and calibration systems. Nevertheless, since the pump source is potentially a critical point for such systems, there is a huge need to assess their reliability in space environment, especially in terms of operation under vacuum conditions. We have then studied the electro-optical behavior of several 980 nm laser diodes and shown that they may degrade more rapidly when submitted to a vacuum environment. Then, spatially resolved temperature variations have been measured by thermoreflectance on the laser diode front facet and have shown a temperature variation increase under vacuum conditions, in particular near the emission region, where a catastrophic optical damage is most likely to occur. This temperature variation increase could then be one of the causes for the more rapid laser diode degradation.

Photonic systems are more and more used for aerospace applications and most of these systems require reliable optoelectronic emitters or photodetectors such as Laser diodes or phototransistors. Examples of satellite applications including such devices consist in time reference (atomic clock), attitude control (Fiber Optic Gyroscope) and telecommunications (inter-satellite links and satellite-downlinks). In order to ensure reliability of photonic devices for space applications, a critical issue requires to correctly evaluate their degradation with respect to the constraints of various mission profiles. In particular, the wide range of satellite missions for LEO (Low Earth Orbit), GEO (Geostationary Earth Orbit) or MEO (Medium Earth Orbit) environment, makes currently qualification activities very challenging. Selection tests and life-testing are specifically based on optical telecommunication standards (ex. Telcordia GR-468 CORE) for reliability prediction. Basically, this approach uses the extrapolation of degradation from electrical or optical parameters monitoring and occasionally physics of failure on a weak statistic population allowing both strong test time reduction and long-term reliability prediction. Unfortunately in the case of mature technology, there is a huge complexity in order to calculate average lifetime and failure rates (FITs) using aging tests in particular due to extremely low failure rates. For instance, regarding Laser diode technologies, times to failure tend to be 106 hours under typical conditions (10 mW, 80°C). These aging tests must be performed on more than 100 components aged during 10,000 hours mixing different temperatures and drive current conditions conducting to acceleration factor above 300. Such conditions are high-cost, time consuming, cannot give a complete distribution of times to failure and highlight that predicted lifetime based on previous standards is no longer effective. In the case of radiation aspects for space environment, the correct estimation of the key performance degradation as a function of the total ionizing dose (TID) and/or the displacement damage dose (DDD) received by the devices in the framework of a specific mission profile, remains also a crucial point to face.

We have step-irradiated Al-free laser diodes with 1 MeV electrons at fluences from 10 14 up to 10 16 electrons/cm 2 . We measure at each step their L-I and I-V characteristics to evaluate the impact of irradiation on optical and electrical properties. We also irradiated a test structure incorporating 3 GaInAsP quantum wells and a thick GaInP cladding. Quantum wells photoluminescence measurements show a strong degradation of its intensity. However laser diodes properties remain essentially unchanged, due to a strong forward bias annealing effect.

CCD imagers have been irradiated with 10 to 100 MeV protons, 45 MeV neutrons and measurements focussed on random telegraph signal (RTS) characterization. The objective is to propose a method for RTS detection and to analyse pixels behaviour with temperature, particle species and energy.

EnglishThe Red River Delta is one of Viet-nam’s major areas of settlement and economic development. Such development was made possible over the centuries by the ceaseless efforts of the Delta’s inhabitants and their successive governments to tame the rivers that criss-cross the Delta in order to curb the risk of flooding and ensure availability of water resources. Rapid economic development has brought about unprecedented and dramatic changes in land use in the Delta, as well as a brisk increase in economic capital invested in this area. Such changes seem to have taken place without the risk of flooding being taken into account objectively, as the illusion persists that the dyke system alone can protect the delta from natural disaster. Should exceptional flooding occur which would exceed the current - and already quite high - level of protection, the resulting situation could turn out to be disastrous for the entire national economy francaisLe delta du fleuve Rouge est l’une des principales zones de peuplement et developpement economique du Viet-nam. Pour rendre ce developpement possible, et ce depuis des siecles deja, les habitants du Delta et leurs gouvernements successifs n’ont eu de cesse que de domestiquer les cours d’eau qui le sillonnent pour maitriser tant les risques d’inondation que la disponibilite de la ressource en eau. Avec l’acceleration du developpement economique, se dessine, sans doute pour la premiere fois de l’histoire, un profond bouleversement de l’occupation des sols dans le delta et une tres forte augmentation du capital economique immobilise sur cette zone, sans que la contrainte d’inondation ne semble etre prise en compte objectivement, chacun ayant l’illusion que le reseau de digues suffit a proteger le delta de toute catastrophe naturelle. Il en resulte une situation qui pourrait reellement s’averer catastrophique pour l’economie nationale toute entiere en cas de crue exceptionnelle qui excederait le niveau de protection (deja relativement eleve) atteint.

In this study, we report in protons radiations damages on Europeans manufactured Commercial Of The Shelf (COTS) Light Emitting Diodes (LED). The aim of this study was to assess the potentiality of such devices for space applications. In total, fifteen references coming from three different manufacturers have been tested. All devices have been stepirradiated with 50 MeV protons, up to a fluence of 2.5E12 protons/cm². Light output, I-V characteristics and emission spectra were measured.

Pump laser diodes emitting at 980 nm are typically used in distribution network transmission systems in order to amplify C+L band signals for long distance optical telecommunication systems and are now implemented in space missions especially for Fiber Optic Gyroscopes (FOGs) and foreseen for intra-satellite communication links and calibration systems. However as the pump source is potentially a critical point for such systems, there is a huge need to assess their reliability in space environment, especially in terms of operation under vacuum conditions. Some published studies have been already reported on qualification results of high power 808nm pump laser diodes arrays in vacuum environment especially for NASA future space missions. Because no catastrophic failures were observed, the authors concluded that the laser diodes are robust enough to survive in the harsh space environment. Nevertheless, regarding both complexity of space environment and variety of Laser diode technologies, a good understanding of the physics of failure and an appropriate testing method are crucial to scope high levels of reliability. However up to now, long term in-vacuum reliability testing of 980nm laser diodes was never clearly addressed. Because the chip is embedded into a sealed package, this last is not directly exposed to vacuum environment but depending on the package leak rate, the internal pressure may vary from its initial value to the external pressure one.

International audience; This paper focuses on the Dark Current-Random Telegraph Signal (DC-RTS) in solid-state image sensors. The DC-RTS is investigated in several bulk materials, for different surface interfaces and for different trench isolation interfaces. The main parameter used to characterize the DC-RTS is the transition maximum amplitude which seems to be the most appropriate for studying the phenomenon and identifying its origin. Proton, neutron and Co-60 Gamma-ray irradiations are used to study DC-RTS induced by both Total Ionizing Dose (TID) and Displacement damage (Dd) dose. Conclusions are drawn by analyzing the correlation between the exponential slope of the transition maximum amplitude histogram and the location of the DC-RTS-induced defects. The presented results can be extrapolated to predict DC-RTS distributions in various kinds of solid state image sensors.

The effect of strain on threshold current and differential gain in 1.55 μm InGaAs/InGaAsP quantum well lasers is reviewed. A constant decrease in the threshold current with increasing stress is predicted if a conventional model of Auger recombination is used. We propose a more realistic model based on an accurate method for the derivation of the Auger recombination rate in quantum wells. Unlike the conventional theory, a realistic valence band structure along with Fermi–Dirac statistics and analytic expressions of the transition matrix element for both bound–bound and bound-unbound Auger processes are employed. Contrary to conventional modeling, computation results show an optimal compressive strain of approximately 1% that minimizes the threshold current and maximizes the differential gain. These results are in good agreement with the experimental results reported in the literature.

In the last decade, there has been increased interest in photonic technology for new satellite applications. One critical issue is the high sensitivity to radiative environments of the Erbium Doped Fiber (EDF). It leads to a radiation-induced absorption (RIA) that is not due to erbium content but mainly to the aluminium that ensures the erbium inclusion in glass. As the radiation induced losses grow as an exponential function of fiber length, the principal way so far to reduce EDFA degradation has consisted in increasing erbium concentration using conventional doping techniques. However, this is limited by the quenching effect, which impacts the fiber length needed to reach high gain, but also by the Aluminium-induced RIA. It has been recently proposed an original nanoparticle (NP) doping approach, which allows codopant content decrease with reduced quenching impact, while keeping EDF amplifying performances. A radiation-resistant amplifier can thus be designed as a "quenching-free", heavily-erbium-doped amplifier with low RIA. We demonstrate for the first time an aluminium-free EDF, exhibiting low quenching and low RIA. Despite the lack of aluminium, using silica NPs allows an erbium concentration close to the one of standard EDFs (200 ppm). This fiber is compared to a 1400 ppm Erbium-doped optical fiber with a strong aluminium concentration. Whereas the two fibers exhibit similar initial optical gain (15 dB under saturation conditions), the NP doped Al-free EDF shows only 2 dB gain reduction after a 600 Gy gamma deposit, while the Al/Er EDF incurs more than 10 dB gain degradation.

International audience; In the last decade, there has been increased interest in photonic technology for new satellite applications. One critical issue is the high sensitivity to radiative environments of the Erbium Doped Fiber (EDF). It leads to a radiation-induced absorption (RIA) that is not due to erbium content but mainly to the aluminium that ensures the erbium inclusion in glass. As the radiation induced losses grow as an exponential function of fiber length, the principal way so far to reduce EDFA degradation has consisted in increasing erbium concentration using conventional doping techniques. However, this is limited by the quenching effect, which impacts the fiber length needed to reach high gain, but also by the Aluminium-induced RIA. It has been recently proposed an original nanoparticle (NP) doping approach, which allows codopant content decrease with reduced quenching impact, while keeping EDF amplifying performances. A radiation-resistant amplifier can thus be designed as a "quenching-free", heavily-erbium-doped amplifier with low RIA. We demonstrate for the first time an aluminium-free EDF, exhibiting low quenching and low RIA. Despite the lack of aluminium, using silica NPs allows an erbium concentration close to the one of standard EDFs (200 ppm). This fiber is compared to a 1400 ppm Erbium-doped optical fiber with a strong aluminium concentration. Whereas the two fibers exhibit similar initial optical gain (15 dB under saturation conditions), the NP doped Al-free EDF shows only 2 dB gain reduction after a 600 Gy gamma deposit, while the Al/Er EDF incurs more than 10 dB gain degradation.

This paper reports the hardening principles and the first characterization of an optocoupler structure that uses a Vertical Cavity Surface Emitting Laser (VCSEL) as a light emitter. Current Transfer Ratio (CTR) measurements carried out before and after proton irradiations show that this architecture improves the radiation hardness by a factor of 10 or more above the present state-of-the-art hardened optocouplers.

We demonstrate for the first time a radiationresistant Erbium-Doped Fiber exhibiting performances that can fill the requirements of Erbium-Doped Fiber Amplifiers for space applications. This is based on an Aluminum co-doping atom reduction enabled by Nanoparticules Doping-Process. For this purpose, we developed several fibers containing very different erbium and aluminum concentrations, and tested them in the same optical amplifier configuration. This work allows to bring to the fore a highly radiation resistant Erbium-doped pure silica optical fiber exhibiting a low quenching level. This result is an important step as the EDFA is increasingly recognized as an enabling technology for the extensive use of photonic sub-systems in future satellites.

The qualification of erbium-doped fibers for space applications is made complex because they exhibit enhanced low-dose-rate sensitivity. We demonstrate a new assessment method that allows these optical fibers to be tested over a short time, which can be extended to any photonic device.

Degradation of packaged light-emitting diodes (LEDs) under gamma irradiations has been investigated using usual electro-optical characterizations. Failure mechanisms have been revealed by an accurate degradation model taking into account the Stark effect in electroluminescence spectrum and piezoelectric field in the active zone. Gamma irradiations have induced an additional mechanical stress close to 0.25 MPa in the active layer resulting from the change of the polymer mechanical properties used on the LED package.