Application Of Sub-carrier Modulation In Optical Access Network

As the diverse services are emerging such as IPTV,HDTV,and Mobile TV , bandwidth requirement is more increasing and the traditional access network fails to meet the development of the new services. In the background, WDM-PON and RoF(Radio over Fiber) technologies become research hotspots because they greatly enlarge the bandwidth of the access network and can meet the requirements of new services. WDM-PON and RoF are studied to provide wired and wireless broadband service, respectively.However, both wired and wireless services are needed in daily life. Therefore, it is greatly significant that the Sub-Carrier Modulation is applied in optical access network to build a hybrid access network of WDM-PON and RoF. In the article, we review firstly the application of Sub-Carrier Modulation technology in WDM-PON and RoF including how to use the technology to realize multicast and the uplink transmission in WDM-PON and how to use it to generate optical millimeter-wave in RoF. Next, after we study the existing solutions of hybrid access network of WDM-PON and RoF based on filter, a hybrid access network of WDM-PON and RoF based on orthogonal modulation is proposed in this article. In the hybrid access network, the optical carriers modulated by unicast data are remodulated by RF signal. Unicast data and RF signal are received through different demodulation schemes at the sink, respectively. The proposed hybrid access network is demonstrated by simulation in VPI.In order to improve the performance of the hybrid access network of WDM-PON and RoF, the OSSB(Optical Single Side-Band)modulation is investigated subsequently. Because the OSSB signal has capacity of dispersion tolerance, it is benefit to use the OSSB signal in the hybrid access network of WDM-PON and RoF. On the basis of the existing OSSB modulation technologies, we present a new OSSB modulation technology based on IL-FPLD(Injection Locked Fabry-Perot Laser Diode)in this paper. In the modulation, IL-FPLD is modulated by data. the OCS-DSB(Optical Carrier Suppressed- Double Side-Band) signal is processed by IL-FPLD . In the process, one side-band of OCS-DSB signal is amplified and modulated by data. The other side-band is restrained due to the mode-locked characteristic of IL-FPLD.The OSSB signal is generated by merging the processed signal and the optical carrier. That the OSSB modulation technology based on IL-FPLD can generated good OSSB signal is verified by simulation in VPI.