| Summary: | 碩士 === 國立成功大學 === 光電科學與工程研究所 === 95 === Spectra-amplitude-coding Optical Code-Division Multiple-Access (SAC-OCDMA) is the most appropriate way for signal transmitting because it is uncomplicated and the information data can be regenerated without any synchronization. Besides, the decoder applies balance detection to suppress the multiple-access interference (MAI). However, chromatic dispersion from optical fiber produces temporal skews and destroys the rectangular structure of code patterns in the SAC-OCDMA system. Thus, the balance detection doesn’t work and the system performance will be degraded.
To improve the system performance, dispersion optical equalizers are needed. In this study, we apply cascaded Mach–Zehnder interferometers (MZIs) to design a dispersion slope equalizer for the SAC-OCDMA system. The dispersion slope of cascaded MZIs compensator based on silica-based planar lightwave circuit (PLC) could be adjusted by the arm length differences of MZIs and be complementary with the fiber links.
We present two sets of MZI length differences for 10 km-long and 20 km-long single-mode fibers and verify the compensation skill by relative delay time slope and signal-to-interference ratio (SIR). The dispersion slope equalizer with perfect complementary slope successfully compensates the dispersion from single-mode fibers and the system performance with dispersion slope equalizer is highly improved.
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