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This field trial transmits 1.5Tb/s superchannel with 5b/s/Hz spectral efficiency over 875km of EDFA-amplified SMF, using six 250Gb/s real time elastic transponders featuring 1dB minimum Q margin over 48 hours. Channels are 50GHz spaced.

Numerous techniques have been used to improve the breakdown voltage (VBR) capability of high voltage devices with the aim of getting closer to the breakdown voltage of a plane parallel junction. In this work, a peripheral protection for a 3 kV SiC bipolar diode is presented. This protection concept is based on a large and deep trench filled by an insulating material. This trench is called Deep Trench Termination (DT2) already validated in Si technology. Our results show that, on the basis of simulations with TCAD Sentaurus, it is possible to protect effectively with this type of trench. The simulation allows to optimize the characteristics of peripheral protection. To take into account the close environment of the semiconductor, the positive and negative fixed charges at the semiconductor - insulating interface have been considered. The work was focused on a 3 kV SiC bipolar diode, but the proposed solutions could be easily scale to any range of voltage.

Seaside nuclear power plants have to face the ageing of nuclear reactor cooling piping systems. In order to minimize the duration of the production unit shutdown, maintenance operations have to be planned well in advance. In a context where owners of infrastructures tend to extend the life span of their goods while having to keep the safety level maximum, Oxand brings its expertise and know-how in management of infrastructures life cycle. A dedicated methodology relies on several modules that all participate in fixing network optimum replacement dates: expertise on ageing mechanisms (corrosion, cement degradation...) and the associated kinetics, expertise on impacts of ageing on functional integrity of piping systems. predictive simulation based on experience feedback, development of monitoring techniques focused on actual threats. More precisely, Oxand has designed a patented monitoring technique based on optic fiber sensors, which aims at controlling the deterioration level of piping systems. This preventive maintenance enables the owner to determine criteria for network replacement based on degradation impacts. This approach helps the owner justify his maintenance strategy and allows him to demonstrate the management of safety level. More generally, all monitoring techniques used by the owners are developed and coupled to predictive simulation tools, notably thanks to processes based on Bayesian approaches. Methodologies to evaluate and optimize operation budgets, depending on predictions of future functional deterioration and available maintenance solutions are also developed and applied. Finally, all information related to infrastructure ageing and available maintenance options are put together to reach the right solution for safe and performing infrastructure management.

PROBLEM: Alloimmunization as a treatment for recurrent spontaneous abortion (RSA) is still controversial due to the lack of enough controls to evaluate its effectiveness. The present study was conducted to compare the live birth rate in the presence or absence of immunotherapy. METHOD OF STUDY: Ninety-two women with RSA (79 primary [PA] and 13 secondary aborters[SA]) received immunotherapy. Thirty-seven RSA couples not receiving paternal alloimmunization, constituted the “control” group. RESULTS: The pregnancy rate in alloimmunized was 58 vs 46% in the control group. The live birth increased from 71% in the controls to 88% after immunotherapy. The alloimmunization induced mixed lymphocyte reaction blocking factors (MLR BFs) in 79% of women. However, they were also present in 83% of immunized women experiencing a new abortion. CONCLUSION: These results indicate that alloimmunization may be useful in the treatment of RSA.

It has been proposed recently that the lowest level of dc field, above which electrical degradation may occur, is associated with the formation of space charges in insulation. Therefore, inference of field levels above which space charge accumulates in a given material may provide fundamental information for material characterization and system design. Threshold field values were estimated through evidence of space charge accumulation derived from conduction current, space charge amplitude and electroluminescence (EL) counts vs, electrical field characteristics. Press-molded plates of polyethylene-based materials were used for this investigation. In order to be able to detect even by EL experiments the presence of the space charge accumulated at low fields, measurements were carried out during both polarization and short-circuit of specimens. It is shown that the threshold corresponding to the onset of EL upon grounding the specimen is close to the space charge accumulation threshold derived from space charge and conduction current measurements. This earlier value is considerably lower than the one previously detected from constant dc-voltage EL measurements, thus confirming that even at low fields and in the presence of voltage reversals or transients, space charges can trigger luminescence phenomena. The methodology developed in this paper enlarges the applicability of the EL technique to accommodate a wider electrical field range in view of insulation characterization.

Wavelength-resolved electroluminescence and current measurements have been performed on polyethylene naphthalate thin films submitted to high direct current fields (3.4 MV cm-1) for several days. The change in the shape of the emission spectrum over time resembles that observed in short-term experiments when the field is increased. This behaviour provides the basis for a model in which the time evolution of the spectrum shape is attributed to the progressive charging of the material, through homopolar injection. The net result is an increase of the internal field in the charge-free region where luminescence occurs.

This paper presents an experimental study of Partial Discharges and light emission with ceramic substrates embedded in silicone oil, under ac and square high voltage. Two types of ceramic materials used in power electronics modules are considered: Aluminum Nitrite (AlN) and Alumina (Al2O3). With AlN, a large light emission due to the electroluminescence of the ceramics occurs during the negative dV/dt. This phenomenon is not observed with Al2O3. With Al2O3 and silicon oil, the light emitted is only due to PDs, and recording under square voltage wave shows that PDs are more numerous and/or more intense compared to ac. Square voltage is more relevant to actual working conditions within power electronics modules than ac.

The introduction of bit rate variable transceivers is expected to improve network reconfiguration and optimization. The different network margins are discussed along with the related strategies to reduce them.

In Insulated gate Bipolar Transistor (IGBT) modules, ceramic substrates are used as insulation between semiconductor chips and the ground potential. The substrate, semiconductor chips and connections are covered with silicone gel to prevent partial discharges (PDs) from occurring. In this work, partial discharges are investigated on laboratory samples made of metalized substrates embedded in silicone gel and various liquids. Substrates are made of aluminum nitride (AlN), alumina (Al2O3), or glass/epoxy composite. The objective is to determine the actual origin of PDs, by changing the nature of encapsulating material and substrate. The various liquids used are first characterized using a point-plane geometry. Experiments show that a rather large discrepancy on the PD behavior can be due to the ceramic substrate itself. "Good" and "bad" substrates can be identified on the basis of PD measurements. The influence of the sample preparation (degassing procedure) is also evidenced. The main conclusion obtained in this paper shows that partial discharges do not occur within the encapsulating material, contrary to most previous hypotheses, but within pores existing in sintered ceramic materials. Changing the substrate nature has a large influence on PD behavior, whereas a modification of the encapsulating material has almost no effect.

Aluminium nitrite (AlN) or alumina (Al 2 O 3 ) substrates are widely used in power electronics modules, due to their ability to provide both electrical insulation, and heat conduction properties. A silicon gel usually covers the substrate, semiconductor chips, and bondings to prevent partial discharges (PD) from occurring within the module. However, at high voltage PDs can be observed in high electric field regions, mainly at the sharp edges of copper tracks on the substrate. In this study, we try to determine the origin of these PDs. Phase resolved PD recordings (PRPD) and optical visualization at very high sensitivity are carried out on substrates embedded in gel or insulating liquids. PD features are very different from those obtained in needle-plane geometry in gel or liquid, and do not depend on the nature of the liquid or gel. The main conclusion is that PDs recorded with substrates originate from the ceramic material itself, due to the presence of numerous μm-sized pores in sintered materials.

The laser induced pressure pulse method -LIPP- is commonly used for measurement of distribution of space charge in insulating materials. The aim of this paper is to study the mechanisms giving rise to the generation of the pressure pulse and to optimize the generating process to obtain the better sensitivity of the technique. For transparent liquids at the laser wavelength, the two mechanisms which may generate the pressure pulse, i.e. thermal expansion and thermal vaporization at the liquid/target interface, are clearly identified depending on the laser energy. The surface roughness of the target also played an important role in this generation. For opaque liquids, thermal dilatation and evaporation at the liquid/air interface are involved. With the use of Indian ink, the energetic conversion revealed better for the smaller investigated liquid thickness, i.e. 20 µm. A concentration of 20% of Indian ink in water provides the best sensitivity at 20°C, respectively 25% at 60°C.

Aluminium nitrite (AlN) or alumina (Al 2 O 3 ) substrates are widely used in power electronics modules, due to their ability to provide both electrical insulation, and heat conduction properties. A gel layer usually covers the substrate, semiconductor chips, and bondings to prevent partial discharges (PD) from occurring within the module. However, at high voltage PDs can be observed in high electric field regions, mainly at the sharp edges of copper tracks on the substrate. In this study, we try to determine the origin of these PDs. Phase resolved PD recordings (PRPD) and optical visualisation at very high sensitivity are carried out on substrates embedded in gel or insulating liquids. PD features are very different from those obtained in needle-plane geometry in gel or liquid. The main conclusion is that PDs of low amplitudes probably originate from the ceramic itself, due to the presence of numerous µm-sized pores in sintered materials.

We compare the performance of 40G and 100G coherent PDM-QPSK solutions for the upgrade of existing 10G-based optical networks. This comparison is performed on the Alcatel-Lucent 1626LM commercial system.

In this paper, we have investigated the behavior of dielectric properties (partial discharges) of liquids of different natures (silicon oil, aromatic liquid). Partial discharges measurements have been done over the voltage range (0-25 kVpp). Two types of devices have been analyzed. The first one consists of a ceramic covered by liquid, the second one of a needle-plane system embedded in liquid. The origin of partial discharges for the both devices is discussed. A mixture of corona effect and discharge in micro voids appear for the ceramic based system whereas only the corona effect was identified for the second one. Results are then discussed in correlation with potential applications in power electronic components where rubber and gel are used for IGBT module.

Silicone gels are widely used to encapsulate power electronics modules. The objective of this paper is to study the partial discharge (PD) mechanism in a silicone gel, using electrical measurements and fast visualization. Experiments are carried out in a pointplane geometry, using either impulse voltage or ac. Under impulse voltage, the visualization shows that the first discharges recorded in a new sample are due to the initiation and propagation of "streamers", with features close to those previously reported in viscous liquids. Under ac, a stable PD regime rapidly establishes: a streamer creates a cavity with a long lifetime, and PDs occur in this cavity during the subsequent ac waves. Since slow streamers develop during long times (some ms), classical PD measurements do not provide an adequate evaluation of the actual discharge magnitude: very small PDs (1 pC) are recorded, whereas large cavities with a total charge in excess of 10 pC are actually present in the gel. When PDs are repeated permanent degradations of the gel rapidly occur, showing the limited self-healing capabilities of silicone gels.

In order to increase the knowledge of the processes involved during the degradation of insulating silicone gels under ac stress, recordings of the activity of partial discharges (PD) are performed. Silicone gels are commonly used for the insulation and packaging of high voltage semiconductors such as IGBT modules. We worked on a commercially available dielectric silicone gel. Electrical and optical apparatus allows the measurement of PD's and their location, either on actual power module substrates, or in a point-plane gap. The temperature dependence of PD inception voltage is moderate, while the number of PD's and their charge steeply increases versus temperature. We show that the formation of cavities constitutes the main factor responsible for the degradation under ac conditions. The actual self-healing capabilities of silicone gels are also studied and discussed.

The intent of this paper is to cross-correlate the information obtained by space charge profile analysis and electroluminescence (EL) detection in crass-linked polyethylene samples submitted to de fields, with the objective to make a link between space charge phenomena and energy release as revealed by detection of visible photons. Space charge measurements carried out at different electrical fields by the pulsed electro-acoustic method show the presence of a low-field threshold, close to 15 to 20 kV/mm, above which space charge begins to accumulate considerably in the insulation. Charges are seen to cross the insulation thickness through a packet-like behavior at higher fields, starting at about 60 to 70 kV/mm. EL measurements show the existence of two distinct thresholds, one related to the permanent excitation of EL under voltage, the other being transient EL detected upon specimen short-circuit. The former occurs at values of field corresponding to space charge packet formation, and the latter to the on-set of space charge accumulation. The two techniques give therefore consistent information on space charge phenomena and associated energy release in the optical EM spectrum.

Power module reliability can be increased if problems due to high electric fields can be better understood. This paper proposes a global analysis using finite element simulations. Results are confirmed thanks to optical detection of partial discharge localization. Solutions to reduce field reinforcement are proposed and discussed. A discussion of maximum electric field handled by insulation gel is also provided.

Under DC stress, electroluminescence in polyethylene naphthalate films is stable, current-proportional, above a threshold field of 150 kV/mm. At this field level, the luminescence is thought to be triggered by impact excitation and/or ionization of the luminescent centers by hot electrons, or, alternatively, by electron and hole injection, migration and recombination. Investigation of the internal space charge distribution versus field is believed to constitute a relevant approach to discuss the excitation process.

Today, high voltage power semiconductors such as IGBTs, are being developed. As the voltage is increased, local electric fields applied to dielectric materials also increase. Local deterioration of dielectric materials due to partial discharges (PD) may appear and affect the reliability of the whole component. The usual way to detect PD's under ac voltage via electrical measurements is no longer applicable with the pulsed voltage wave shape encountered in power semiconductor applications. This paper presents investigations carried out with optical measurements of PD's in silicone gels, in a typical IGBT module structure. In addition, a very faint light emission is detected below the PD inception voltage. This light can presumably be attributed to an electroluminescence phenomena, such as previously reported in solids or aromatic liquids, and can constitute a non destructive technique that allows to detect the existence of local high fields in the gel.