Algorithms of Chromatic Dispersion Equalization in Coherent Optical Communication Systems

In order to respond to the technologic society expectations and satisfying the nowadays search of services who required a high spectral efficiency, emerge an interest about coherent optical systems, that allows multi-level modulation formats and digital signal processing. So, the study of performance of equalization algorithms at digital domain is essential in order to get the best solutions. The purpose of this paper is to describe the optical homodyne receiver, show the results about chromatic dispersion equalization and study the performance by signal-to-noise ratio estimation (SNR). Initially, the paper describes the homodyne detection and chromatic dispersion and then is presented SNR estimation techniques and equalization algorithms. At first the fixed chromatic dispersion equalization is approached by Overlap-Save algorithm and later the residual chromatic dispersion equalization (resulting from the variation of fiber dispersion parameter due to thermal variations) by LMS algorithm.