Pre-correction adaptive optics performance of a 10 km laser link

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. We show that AO pre-correction is most advantageous for low point ahead angles (PAAs), as expected. In addition, an optimum AO pre-correction performance is found at 16 AO modes for the experimental conditions. For the specific test site, tip-tilt pre-correction 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.