| WDM-PON is considered to be the best networking model for the next generation PONs technology, which uses optical wavelength division multiplexing technology, in fact, is a virtual point to point two-way communication, and is able to realize the true meaning symmetric rate of upstream and downstream signal. WDM-PON can better take advantage of the tremendous bandwidth of the optical fiber, and is able to provide users with higher access bandwidth. WDM-PON compared with TDM-PON which based on time division multiplexing, has a great advantage in security of information transmission, network management, maximum transmission distance, as well as symmetric rate of upstream and downstream signal.The high cost of optical components is one of the most important factors that limit the development of WDM-PON, the key technical issues is using "colorless" ONU technology in WDM-PON system, which can reduce the installation, operation and maintenance costs. In this thesis, using RSOA to achieve "colorless" ONU, its principle is:the system only setting light source at the OLT side, no light source at the ONU side but using RSOA to replace it. Part of the downstream optical signal is used as a re-modulated optical carrier, the upstream signal is modulated on to this part of optical signal, and then transferred back to the OLT side. RSOA is used as both light emitter and modulator in the WDM-PON system, and it also can generate extra gain to overcome the loss in the transmission, reducing the use of the optical amplifier.In This paper, based on introducing the working principle and the key technology of WDM-PON, focused on researching re-modulation WDM-PON system based on RSOA. The paper introduces and analyzes several new types of modulation format’s generation and demodulation principle, introduced the mixed modulation technique to the WDM-PON, designed and implemented Based the RSOA re-modulation WDM-PON system using DPSK/OOK, RZ-DPSK/OOK, DQPSK/OOK code. Also focusing on introducing a new proposed staggered differential phase modulation code (SDPSK), and trying to introduce it into WDM-PON, discussing whether if this code with a variety of advantages can improve the performance of WDM-PON system or not. The following is a brief introduction for the paper’s main work and innovation points:1ã€studied the development of PON technology at home and abroad, and focused on the development status of the WDM-PON, and analyzed the advantages and disadvantages of the key technologies of WDM-PON.2ã€Introduced the mixed modulation technology into WDM-PON, and analyzed the generation and demodulation process of some new modulation formats, through studying characteristics of these code such as spectral characteristics, duty cycle to analysis their advantages and disadvantages in depth.3ã€Studied the structure and working principle of RSOA, especially focused on studying the saturated gain effect. Using RSOA is a good way to achieve "colorless" ONU, designed and implemented DPSK/RZ-DPSK/DQPSK WDM-PON system combined with mixed modulation, and analyzed the performance of the various systems.4ã€Introduced a new modulation format:staggered differential phase modulation code (SDPSK), it has the advantages of high spectral efficiency, large capacity like DQPSK, but has a more simpler demodulation than DQPSK. Studied its generation and demodulation principle and tried to introduce this code into WDM-PON, discussing whether if this code with a variety of advantages can improve WDM-PON system performance or not. |
