Objective: To develop a phased-array photonics circuit for phase-shifting of multiple transmit beams in optical feeder-link ground stations and to demonstrate its ability to compensate for atmospheric turbulence by means of wave-front pre-distortion.
Targeted Improvements:Feeder link technology based on photonics phase shifters, without deformable mirrors.Deformable mirrors can be used topre-distort the laser beam in ground-to-space optical links to compensate for the beam spreading effects of atmospheric turbulence which, if left uncorrected, would seriously degrade or disrupt communication. An alternative approach is to use multiple laser beamsarranged in a phased array.
The advantages of this approach are that no moving parts are required and that fine beam steering can also be performed by the phased array. With the development of low insertion loss, multiple channel photonic phase shifters this implementation becomes feasible. The outcome of the activity will be a breadboard of a feeder link system that implements beam pre-distortion by measuring incoming wave-front distortions using a classical wave-front sensor and computing and applying individual local phase shifts to multiple (~100) feeder link beams. The breadboard shall also demonstrate the transmission of up to 50 W of optical power distributed over a number of sub-apertures.