We demonstrate for the first time a radiation-resistant 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.

Optical feeders for geostationary High Throughput Satellites (HTS) systems based on 1.55µm wavelength technology are expected to enable to transmit up to several terabits over one active link. A desirable option of transmission architecture is an optical feeder link transparent with respect to the user air interface. This can be implemented using either a digital or an analog modulation of the optical carrier. The digital option increases the optical bandwidth to be transmitted, however it benefits from error correcting codes, interleaving and framing which are efficient against atmospheric turbulence impairments. The analog option is more efficient concerning the optical bandwidth; however the atmospheric turbulence impairments can only be mitigated by a more complex optical ground terminal. Both analog and digital options could be feasible in the 2025-2030 time-frames but the digital option is more mature with respect to the atmosphere impairments mitigation techniques.

A new theoretical framework is proposed to explain the dose and dose-rate dependence of radiation-induced absorption in optical fibers. A first-order dispersive kinetics model is used to simulate the growth of the density of color centers during an irradiation. This model succeeds in explaining the enhanced low dose rate sensitivity observed in certain kinds of erbium-doped optical fiber and provides some insight into the physical reasons behind this sensitivity.

The motivations and application framework for the introduction of all-optical wavelength division multiplexing (WDM) transmission and routing techniques in the transport network are presented. The requirements and functionalities of all-optical transparent routing nodes are discussed, and the physical architecture of a crossconnection node is proposed, to meet these requirements. Optical devices suitable for the node implementation are compared, and first demonstrations of crossconnection function at data rates up to 10 Gb/s are given. These results bring experimental evidence of the high potential of all-optical routing nodes for actual implementation of multiwavelength transport networks.

We describe an original technique that permits a specially accurate measurement of the variations of the transmittance of optical fibers vs the incidence of launched light. For large-diameter large-aperture fibers, which prefer light power transmission, the transmittance may be modeled using geometric optics. Taking into account the reflection losses at both ends, the core attenuation and a very weak lack of reflectivity at the core-cladding interface, good agreement is obtained between calculated variations and experimental results for the three kinds of fiber tested. The remaining difference has to be attributed to the mode coupling process which may be thus evaluated. The too high attenuation coefficient, which is attributed to the cladding to account for the losses at the core-cladding interface, characterizes in fact a thin perturbed layer where the materials contact. Thus, this method is a good means to evaluate separately the various processes contributing to the attenuation of open beams along the fibers and to determine which process should be worked on to improve the transmittance.