There has been a great interest to increase the transmission capacity and distance of a repeaterless submarine system for island-hopping applications. For this purpose, it is essential to use WDM technology and high-power optical amplifiers.
In this thesis, we demonstrated a 160 Gb/s(10 Gb/s × 16 ch)WDM transmission system over 200 km of single mode fiber(SMF). To maximize the repeaterless transmission distance, we increased the transmitter's output power to 10 dBm/ch using a high-power (saturation output power ＞ 22 dBm) boost qamplifier, and compensated the fiber dispersion using dispersion compensating fiber(DCF).
The effects of various fiber nonlinearities caused by high optical power within fiber could be neglected due to the large dispersion of conventional SMF.
For the dispersion compensation, we evaluated both the pre-compensation and the post-compensation techniques. The results show that the post-compensation is better than the pre-compensation. This is because, when the pre-compensation technique is used, the high output power of transmitter and large dispersion of DCF degrade the signal through self phase modulation (SPM) ＆ beating between the pulse. The SPM and dispersion-induced chirp interact each other and affect the pulse shape. Thus, the best system performance can be achieved when these two chirps interfere destructively (i.e, the total chirp is near zero). We experimentally showed that the optimum compensation ratio is 88%, which agrees well with the simulation results.
In summary, we demonstrated the repeaterless 160 Gb/s (10 Gb/s × 16 ch) WDM transmission over 200 km of SMF with 88% post-compensation of the total dispersion. The optical signal to noise ratio (OSNR) and Q were measured to be 19.5 dB and 20 dB, respectively.
