Recently, numerous transoceanic fiber-optic transmission systems have been installed to meet the increasing demand of data and voice traffics between continents. However, there are still many issues to be addressed for the further development of such ultra-long distance transmission systems. For example, it has been demonstrated that wavelength-division-multiplexing (WDM) technologies could also increase the transmission capacity of transoceanic system significantly by transmitting multiple optical signals operating at slightly different wavelengths over the same optical fiber. However, the performance of transoceanic transmission system could be degraded by various factors including the chromatic dispersion, nonlinear interaction between channels, and the finite bandwidth of Erbium-doped fiber amplifier (EDFA), etc. In addition, the maximum transmission distance is limited by the degradation of optical signal-to-noise ratio (OSNR) due to the amplified spontaneous emission (ASE) noise accumulated along the concatenated EDFA chain.
In this thesis, the first successful transoceanic transmission experiment in Korea has been reported. A 40-Gb/s (16 channels x 2.5 Gb/s) WDM signal has been transmitted over 10,880km of conventional single-mode fiber using a 640-km long re-circulating loop. In this experiment, forward error-correction (FEC) code and pre-emphasis technique have been used to overcome the limitation caused by OSNR degradations. After transmission, the performances of all 16 channels were measured to be lower than $10^{-10}$.
