A Study Of Encoder/Decoder Used In OCDM/WDM System

As one of the most prospect schemes for all-optical networks realization, optical code division multiplex (OCDM) system arose people's attention increasingly. In this field, the study of the theory and realization method about optical encode/decode, which is the key technology in OCDM system, become the hotspot. Recently, the method by using superstructure fiber Bragg grating catch people's eyes, because of its good performance as encoder/decoder, potential low price, compact structure, and so on. Using transmission matrix method, the transmission matrix model was established by subdividing the superstructure fiber Bragg grating. Then the relative between the transmission spectrum character and structure of the grating can be analyzed through a directly approach. The result of study shows that only the magnitudes and locations of the phase-shift regions, in the condition of the definite read-in depth, can affect the transmission spectrum curve, and that the magnitudes of the phase-shift regions decided by the code choosing. According as the definite code, one can tailor the transmission spectrum for specific needs by adjusting the ratio C of chip grating length. According the request of OCDM/WDM system, the concrete parameter of grating was designed, and the result of numerical simulation was given by the end. Then we not only make a coding-decoding experiment upon the single-channel system, but also make a channel disturb experiment upon the multi-channels system. The result shows that the SSFBG can realize multi-users communication in one WDM channel. But the users'number is few because of the ultra high speed and the rigor requirement of the transmission system.