Communication performance of free space optical link using wavelength diversity in strong atmospheric turbulence

Atmospheric turbulence can be considered as one of the main problems facing FSO communication systems, which degrades the performance in terms of bit error rate. The objective of this paper is to examine the use of wavelength diversity in free-space optics to mitigate the effect of turbulence on the received optical signal. As the refractive index variation will be different for different wavelengths, the fading is not same for different wavelength and different paths at the same time. The signals traveling through turbulent atmosphere undergo different amount of intensity fluctuations. The effect of atmospheric turbulence and scintillation cause intensity fluctuation of optical beam thus increasing the bit error rate (BER). In this paper wavelength diversity technique is proposed to reduce the fading under strong atmospheric turbulence condition. Mathematical expressions are derived for the estimation of the outage probability under strong atmospheric turbulence conditions and considerable improvement is found using wavelength diversity.