| Along with the developing of optical fiber communication, large-capacity and long-haul fiber transmission system will develop rapidly. With the advantages in spectral efficiency,integration and OAM cost, 40Gb/s system will gradually replace 10Gb/s system. Transmission at so high speed must be severely limited by transmission impairments which include group-velocity dispersion(GVD), polarization mode dispersion(PMD), fiber nonlinear effects, Amplified Spontaneous Emission noise(ASE) from optical amplifiers, crosstalk and so on. The new modulation format is one of the key technologies of 40Gb/s system because of its capability in mitigating transmission impairments. This paper deals with modulation formats for 40Gb/s system and focus on the modulation and demodulation principles. Some improvements advices on modulation formats are presented, and some results by simulations about modulation formats'performance are showed in this paper. |
PDF Full Text Request