Investigations on applicability of modulation formats in coherent optical transmission

The modulation formats play an important role in providing speed and efficiency of the internet and data transmission though optical fiber. The concept of coherency in optical communication has gained popularity because coherent optical communication provides better spectral efficiency, more efficient way of managing non-linear impairments, better sensitivity, an increased capacity with use of DSP (Digital Signal Processing) and a support for the multilevel modulation formats. Coherent communication technology gives rise to advanced modulation formats compared to Intensity Modulation Direct Detection (IM-DD) counterparts. This paper presents a comparison-based analysis to investigate the suitability of various modulation formats available for fiber-optic coherent communication. The selection of a suitable modulation format for coherent optical transmission through fiber is required in order to obtain optimal transmission efficiency and speed.