Flexible optical fiber access networks using wavelength selective switches

The optical switching crosstalk is the important considerable issue in the optical fiber communication system, it tends to the signal distortion and decreasing of the system performance. This dissertation research is proposed a guideline to design a flexible fiber to the x (FTTx) system based on wavelength division multiplexing passive optical network (WDM-PON) combining with wavelength selective switches (WSSs). For the system configuration, the 4 wavelengths-10 ONUs system with the data bit rate of 10-Gbps/λ and 40-Gbps/ λ are studied in this dissertation. Moreover, to be active switching, the dynamic wavelength bandwidth allocation (DWBA) controller is used to control WSSs. The modulation format NRZ-OOK is applied for 10 Gbps/λ system and the advanced modulation format NRZ-DQPSK is applied for 40 Gbps/λ system. The investigation of this dissertation is mainly focus on the improvement of system performance such as the minimum received optical power and power budget related with bit error rate(BER). In order to improve the system performance, the signal distortion reduction methodology is applied by adding the proper delay times in switching characteristics of 3 different types of WSS. The results of investigation come from only the computer simulation by using the commercial OptiSystem software without performing real experiments. The maximum reach of data transmission is limited to 20 km over ITU-T G652.D SMF fiber with the limited BER=10⁻⁴ (without using forward error correction: FEC). As the results based on worst case BER, the received optical power for both system designs are improved after providing proper delay times in switching characteristics of WSS. Obviously, the power budget is improved by about 3 dB after providing 3τ delay time of electro-optic switch for both system designs.