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To overcome data rate limitations of RF communication links with satellites, TNO and Airbus Netherlands envision optical free-space communication feeder links for next generation high throughput satellites. This poster presents a feasibility assessment of such links and the technology needed by means of a link budget and a turbulence model of terabit/s optical links. Based on these parameters, requirements and status of the link-subsystems are discussed, and a roadmap is presented, aimed at achieving terabit per second optical feeder links.

For the next generation of very high throughput communication satellites, free-space optical (FSO) communication between ground stations and geostationary telecommunication satellites is likely to replace conventional RF links. To mitigate atmospheric turbulence, TNO and DLR propose Adaptive Optics (AO) to apply uplink pre-correction. In order to demonstrate the feasibility of AO pre-correction an FSO link has been tested over a 10 km range. This paper shows that AO pre-correction is most advantageous for low point ahead angles (PAAs), as expected. In addition, an optimum AO precorrection performance is found at 16 AO modes for the experimental conditions. For the specific test site, tip-tilt precorrection accounted for 4.5 dB improvement in the link budget. Higher order AO modes accounted for another 1.5 dB improvement in the link budget. From these results it is concluded that AO pre-correction can effectively improve high-throughput optical feeder links.

To overcome data rate limitations of RF communication links with satellites, TNO and DLR envision optical free-space communication feeder links for next generation high throughput satellites. This paper provides a feasibility assessment of such links and the technology needed. The main results of the link budget and the turbulence modeling of terabit/s optical links are presented. Based on these parameters, requirements and status of the link-subsystems are discussed, and a roadmap is presented, aimed at achieving terabit per second optical feeder links.

TNO is developing Deformable Mirror (DM) technology, targeted for aberration correction in high-end Adaptive Optics (AO) applications in the field of lithography, astronomy, space and laser communication. The heart of this deformable mirror technology is a unique actuator technology based on the variable reluctance principle. The main advantages of this technology are the inherent high reliability, linearity (>99%), and high efficiency in terms of force per volume and unit power. Based on this actuator technology TNO built and tested a prototype DM, with 57 actuators, and a mirror diameter of Ø160mm. The test results show a highly linear actuator response, with less than 1% hysteresis over a stroke of 40μm. Atmospheric aberration correction has been shown with these DM's in a free space laser-communication bread board. The same actuator technology is also used in the application of a highly compact Fine Steering Mirror (FSM), with an overall volume of Ø27x30mm, with a Ø20mm mirror. This FSM is targeted for satellite-based lasercommunication terminals. Furthermore, a design study has been carried out to show the scalability of this technology towards large (~Ø1m to ~Ø3m) adaptive (secondary) mirrors with several hundreds, up to thousands of actuators. In this paper these different DM and FSM's are discussed, and the latest test results obtained with the DM prototypes are presented.