Modified Manchester modulation format for high‐speed optical transmission systems

Abstract

A novel advanced modulation format based on Manchester signalling is proposed and assessed for high-speed optical communication systems. The new advanced modulation format known as modified Manchester derived from the combination of Manchester and vestigial sideband (VSB) techniques. Its performance assessed and compared in terms of spectral efficiency, chromatic dispersion tolerance and receiver sensitivity against conventional Manchester, return-to-zero (RZ) and non-RZ (NRZ) (with the same spectral width). The optimisation of the optical filter that performed the VSB filtering on the Manchester signal and its detuning frequency results in the compression of the spectral width of the Manchester signal and thereby enhanced the spectral efficiency of the modified Manchester to about 31.3%. This results in the improvement of dispersion tolerance to ∼140 ps/nm. In comparison with conventional modulation formats, the proposed system can improve the dispersion tolerance by three times more than conventional Manchester, which is 44 ps/nm, and twice more than NRZ, which is 51.8 ps/nm and has a better dispersion tolerance of 31 ps/nm than RZ with dispersion tolerance of 109 ps/nm at a bit-error-rate of 10−9. The improvement in the proposed modulation performance achieved without utilisation of any dispersion compensation module or electronic equalisation.