| The exploding growth of the broadband service on the Internet has put forward higher demands on digitization, broadband, intelligence, and security of the optical network. After upgrading and transformation of the back-bone and the metropolitan network, the optical access network becomes the crucial technique to solve the "last mile" problem. As the connection between the service providers and the terminal customers, the security and survivability are the key issues that could not been ignored. However, the present optical layer of the physical layer has no security at all, which makes the optical access network vulnerable to the eavesdropping and attacking. What's more, due to the structure of the access network is complex, the fiber-fault occurs more frequently. In addition, the fiber-fault detection technique at present is also complex, and the cost of the equipment is huge. As a result, the operation, administration, and maintanaince of the network is inefficient, meanwhile the cost of the network is high.Similar to the white noise, the chaotic laser has the noise-like random fluctuation characteristics, which enables information hiding to realize the secure optical communication. Meanwhile, the autocorrelation features of the chaotic light can be used to detect and locate the fiber-fault on the fiber link. Hence, employing the chaotic light in the access network to realize high-speed, wide-span secure communication, as well as to monitor the fiber-fault online in order to improve the efficiency of the operation, administration and maintainance and reduce the cost of the network becomes the key scientific and technical issue at present for the application research of the chaotic light, which has potential practice value.This dissertation is based on the adequate investigation of the present status of the national and international research. The crucial problems such as polarization division multiplexing (PDM) of chaotic-light based secure communication, the real-time and online fiber-fault monitoring, and the architecture of the wideband chaos based access network, communication system and transmitter module are investigated thoroughly through the theoretical and experimental analysis. The main contributions of this dissertion are as follows.(1) PDM between chaotic-light based secure communications is proposed, which increases the multiplexing dimension of chaos encrypted passive optical network. PDMs between x-polarization and y-polarization chaos encrypted channels, and between a conventional fiber-optic channel and a chaos encrypted channel are experimentally investigated. The bit rate for each channel is 1.25 Gb/s, while the transmission in the standard single-mode fiber (SSMF) can be up to 22.54 km. The effect of the mutual power leakages and the optical launched power at the transmitter side on the Q-factor is experimentally tested and analyzed.(2) A real-time online fault monitoring technique for chaos-based passive optical networks is proposed and experimentally demonstrated. The online fault monitoring is realized in two PON structures, i.e., wavelength-division-multiplexing (WDM) PON and Ethernet PON (EPON), respectively. For WDM-PON, online fiber fault monitoring techniques based on on-line chaotic optical time domain reflectrometry (OL-COTDR), as well as a wavelength tunable COTDR are investigated. The factors influencing the fault location results are explored qualitively and quantitatively. For EPON, the chaos sequence encoder is proposed in order to location the fiber fault precisely. The experimental results show that the monitoring process can operate in parallel with the chaotic optical secure communications, which means that the proposed technique has real-time and online properties. Meanwhile, the faults at beyond 20 km from the OLT can be precisely detected and located.(3) Secure optical communication and fiber-fault monitoring techniques of the ring-and-spur long-reach passive optical network (Ring-and-spur LR-PON) based on wideband chaotic laser are proposed, which can ensure secure information transportation on the ring network while providing a higher level of survivability than that of the tree-topologized passive optical network. The structures of the key elements, the bandwidth-enhanced chaotic-light transmitter, and the wideband bidirectional chaos-based secure communication system which are suitable for the proposed network are designed. The performance of the transmitter, the secure communication system, and the ring-and-spur LR-PON are numerically investigated. In addition, the protection solution and the real-time onine fiber fault monitoring techniques are explored. The results show that the bandwidth of the carrier is more than 20 GHz, which enables bidirectional long distance secure communication between the optical line terminal (OLT) and the optical network unit (ONU). The data rate can reach up to 10 Gb/s for each wavelength channel. Through dispersion compensation, the transmission distance can reach up to 100 km. Meanwhile, the architecture of the network enables changing the direction of data transportation to avoid the fiber fault, as well as monitoring the fiber fault real-timely with the wideband chaotic light.(4) A new structure of the photonic integrated chaotic-optical transmitter is proposed and desighed. The structure of photonic crystal waveguide, active devices and passive devices of the transmitter are investigated. The performance of the proposed transmitter is numerically demonstrated and analyzed. The results show that based on the photonic crystal waveguide, the length of external cavity is shortened to 1.125 millimeter. In addition, the transmitter is able to generate the chaotic light under 6 mA of the injection current of SOA, which reduce the power consumption of the chaotic-optical transmitter. |
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