FSO Communication System with Multi Actuator Adaptive Lens

The Coupling Efficiency (CE) of a beam propagating through the free space to a Single Mode Fiber (SMF) by a lens with focal length f and D aperture size is defined by the ratio of the power coupled to the fiber <;P
_C
> to the average power <; P
_A
> at the aperture plane [1]. In the presence of turbulence, the average CE depends also on the root mean square (RMS) of the wavefront phase (σ
_φ
) distortions as CE̅ = [8/(π
²
D
²
w
²
a)] | ∫∫s exp[- [(x
²
+y
²
)/(w
²
a)] ] ds |
²
exp[-σ
²
φ], where w
_α
= [(λf)/(πw
₀
)] is the projected mode field radius of the fiber on the aperture plane, w
₀
is the radius of the optical fiber mode with integral is performed over the effective area of the receiving aperture [2].