Security Vulnerability And Chaos Technology In Physical Layer Of Optical Network

Nowadays, fiber-optic communication networks are playing a leading role in modern high-speed data transmission network. However, optical security vulnerabilities exist in the physical layer. Optical signal will leak by bending, crosstalk, etc. With interference signal being coupled and injected into the fiber, the communication quality of the original signal degrades.Chaotic signal has a characteristic of continuous high bandwidth spectrum, noise-like time-domain waveform, which can be used as security encryption. Chaotic optical communication system encrypt the message by masking the message with chaotic carrier at the transmitter in the physical layer, the physical device becomes the encryption key, so chaotic communication system is very difficult to break. For the past few years, chaotic communication has achieved the transmission rate above Gbit/s.The research is divided into two parts, the first part studies vulnerability factors(light leakage and inject interference) in optical network physical layer. Light leaking and signal restore in fiber is studied by using clip-on optical coupler, and low loss access is achieved by online fusing a coupler. The simulation shows that the continuous light has the strongest ability in light interference.The second part is mainly based on the analyzing communication performance chaotic communication systems. Numerical simulations of all-optical and electro optical feedback chaotic communication system are performed. And improvements are proposed from the aspect of multi-carrier access and higher security.The effect of optical bandpass filter on chaos synchronization quality is studied for all-optical feedback chaotic communication and WDM system. Simulation results show that the optimal filter bandwidth is 16 GHz and the minimum channel interval is chaotic carrier frequency 16.8GHz while still ensuring the synchronization coefficient>0.9.Communication performance of intensity OFDM transmission in the external electro optical feedback chaotic communication systems is analyzed. The simulation shows that BPSK and 4QAM mapping produces better transmission quality, the corresponding signal to carrier ratios were 4.2 and 5.6.The feasibility of using dispersion module in the feedback loop to produce secondary encryption for the external photoelectric feedback chaotic optical communication system is studied. It is proven that the proposed scheme improves security to the original system by 50 times.