Simplified Estimation Method for Suppressing EDFA Output Signal Fluctuation in Terrestrial Free-space Optical Communication Systems

This paper presents a simplified method for estimating the suppression of atmospheric turbulenceinduced signal fluctuations in terrestrial free-space optical communication (FSOC) systems using an erbium-doped fiber amplifier (EDFA). Traditional methods require solving complex propagation and rate equations; However, we propose a more straightforward approach by directly measuring the output signal power at different input power levels and interpolating the EDFA gain curve. By applying a highpass filter function, we can simply estimate the suppression of optical signal fluctuations. Our method was experimentally validated in a terrestrial FSOC link emulating atmospheric turbulence, and the results showed strong agreement between the estimated and measured output power fluctuations. This approach provides an efficient and accurate means of evaluating the performance of gain-saturated EDFAs in FSOC systems without the need for complex numerical modeling.