Experimental study of 42.72Gb/s and 21.36Gb/s DQPSK in WDM communication system

• Main Authors: Li-Lun Wei, 魏瓅倫
• Other Authors: Hidenori Taga
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/32657658603527971132

碩士 === 國立中山大學 === 光電工程學系研究所 === 99 === The growing demand in the telecommunication systems makes the high speed transmission technology important. The Differential Quadrature Phase Shift Keying (DQPSK) is one of the most attractive and advanced modulation formats in recent years, Compared to the Differential Phase Shift Keying (DPSK), it can double the spectrum efficiency, because it can carry two bits in one symbol. In addition, the DQPSK has excellent tolerance against the chromatic dispersion (CD), the polarization mode dispersion (PMD), the optical filtering due to the optical add and drop multiplexer (OADM) and the optical noise. Compared to other coherent modulation formats, the DQPSK signal can be detected directly through a delay interferometer, and it does not need the local oscillator light, so it reduces the complexity of the system setup. We can say that the DQPSK plays an important role for the next generation system. Wavelength Division Multiplexing system (WDM) multiplexes multiple optical carriers in a single optical fiber by using different wavelength of lasers to carry the signal, therefore, increase the wavelength channels makes the system capacity increase. This master thesis focuses on the performance of the WDM system with the DQPSK modulation format in the long haul transmission system. Experiments to demonstrate the QPSK transmission are discussed. To realize the differential modulation, encoders or decoders are necessary. However, electrical encoder or decoder is hard to realize, so, a program is prepared for the experiment to calculate pre-encoded pattern or pre-decoded sequence in advance. Then, the calculated pattern is loaded in the error detector to measure the bit error rate.