Key Techniques For All Optical Pseudo Random Binary Sequence Generator

With the rapid development of optical communication technology, transmitting rate of communication system and network is growing fast, making increasing attentions paid to network security and secret communication. Pseudo Random Binary Sequence (PRBS) is widely used in these areas involving BER testing, secret transmitting, and spread spectrum modulation. However, high-speed electric field PRBS generator is complex in structure and high in cost. Besides, with rate higher than40Gbps, only optical solutions can be adopted to deal with network security. This dissertation mainly discuss the key technologies all optical Pseudo Random Binary Sequence generator based on all optical XOR, with focuses on the following aspects.1、SOA characteristics are analyzed and the relationship between group velocity dispersion (GVD) and the optical gain is derived based on the Kramers-Kronig relation. A simple scheme to measure the GVD of the SOA is proposed with some computations from the measured gain spectra, and it is verified with the comparison between the analytical simulations and the measurements under the condition of small signal input.2、Simulation and imitation of the transmitting characteristics of Gaussian pulse, as well as imitation of all optical wavelength conversion based on SOA are done on OptiSystem software platform.Influences of optical power and SOA injection current on wavelength conversion performance are also analyzed. Besides, experiment of all-optical wavelength conversion based on TOAD is done.3、The basic principles of all optical XOR based on TOAD are introduced and the experimental system is built. The experimental results are analyzed and concluded by sequence diagram. Output under various parameters is simulated and the parameter setting of XOR is also given with the help of sequence diagram.4、Accurate time-delay control method is proposed in this dissertation, achieving bit-level accurate control of two ways optical signal delay with5d optical stages adopted on feedback. The structure set of optical stages is introduced in detail. The debugging result is analyzed. Output optical power is stable with little power loss, which demonstrates good performance of the5d optical stages.