The H2020 VERTIGO project towards tbit/s optical feeder links

To concurrently cope with the scarcity of RF frequency bands, the growing capacity demand and the required lower cost of the ground segment, Very High Throughput Satellites systems must rely on new technical solutions. Optical feeder links are considered as a promising alternative to surpass classical RF technology, offering assets inherent to optical technologies (large bandwidth, no frequency regulation, low beam divergence, components availability). Nevertheless the potential of this technology shall not conceal the remaining challenges to be overcome to make it relevant for operational missions : clouds, turbulence, power generation and high efficiency modulations. VERTIGO (Very High Throughput Satellite Ground Optical Link) is a 3-year H2020 project funded by the European commission and started mid-2019 focusing on the optical link itself regardless of site diversity aspect and aiming at demonstrating in a ground demonstration required technologies to implement very high capacity optical feeder links. In particular, VERTIGO is built on 3 pillars each addressing a key issue for the implementation of optical feerder links: 1) Throughput increase through the use of advanced schemes with high spectral and power efficiency compared to current modulations used in space, as well as RF-over-Fiber approach. 2) High optical power generation to close the demanding link budgets by developing on-board and ground means to raise the transmitted optical power, not only based on amplifier power increase, but also on incoherent/coherent power combining. 3) Opto-mechanical and digital techniques for the mitigation of atmospheric propagation impairments, to make full use of throughput and power increases. Several demonstrations in-flight or on-ground already demonstrated separately key aspects (atmospheric propagation and impairments mitigation techniques, modulation format, high power…), for the implementation of optical (feeder) links. These aspects are closely linked since the solutions to each of them are necessary but not sufficient to allow for high throughput transmissions. VERTIGO concept is to address each key issue with at least one solution and to combine them in an unprecedented manner. To reach these objectives, VERTIGO will lean on a highly skilled consortium composed of : CREONIC, ETH Zürich, Fraunhofer HHI, Gooch and Housego, Leo Space Photonics RD, ONERA, Thales Research and Technology, Thales Alenia Space in France and Switzerland. This paper will present the VERTIGO project and its status.