Design Challenges in High-Throughput WDM-FSO Systems for Satellite Communications

The key technology to provide Terabit/s links in space is Free Space Optics (FSO) with Wavelength Division Multiplexing (WDM). Here, we report and explain how to elaborate a link budget for WDM-FSO feeder links, i.e., those connecting an Optical Ground Station (OGS) to a satellite. Designing these links is a challenging task, due to the very long distance and the effect of the turbulent atmosphere, both adding severe penalties. Considering a link between a MEO satellite (20000 km altitude) and ground, we estimate all the impairments based on analytic and stochastic models. Then, we determine the system parameters that can provide the expected performance for a 100 Gbit/s link.