Figure 1
From: Turbulence-Resistant FSO Communication Using a Few-Mode Pre-Amplified Receiver

Schematic of FSO using (a) adaptive optics, (b) a FM pre-amplified receiver with (c) its sensitivity as a function of the number of modes.
From: Turbulence-Resistant FSO Communication Using a Few-Mode Pre-Amplified Receiver

Schematic of FSO using (a) adaptive optics, (b) a FM pre-amplified receiver with (c) its sensitivity as a function of the number of modes.