In optical communication system, as the link length increases signal gets more and more distorted. So, it becomes difficult to stimulate the signal. Adaptive filter is a recursive filter, which provides an estimate with minimum mean square.Measurements of the bit error rate at various signal to noise ratios and also at different number of samples in a bit are observed,which represents that an increase in signal to noise ratio or the number of samples in a bit, causes the bit error rate to decrease. Estimation of optical signal using adaptive filter reduces the BER effectively.In a fiber-optic system at long distances or high data rates, the system can be limited either by the losses (attenuation-limited transmission) or, assuming that thelink is not limited by the source or detector speed, by the dispersion of the fiber(dispersion-limited transmission). Here we demonstrate how the optimum link lengthcan be determined in different aspects like Dispersion & attenuation.There are so many...