| Summary: | 博士 === 國立交通大學 === 電信工程系所 === 94 === In this dissertation, we propose and demonstrate three novel techniques for optical performance monitoring (OPM) and impairment mitigation. The first one is proposed for dispersion monitoring at 40 Gb/s or beyond, and it is a novel post-detection method based on an optical delay-and-add filter (DAF). The proposed method can be used with or without a pilot tone, and works well even when there exists a residual chirp due to the finite DC extinction ratio of a Mach Zehnder (MZ) modulator or self-phase modulation (SPM). The second technique is proposed and demonstrated for monitoring the timing alignment between a pulse carver and a phase modulator in RZ differential phase shift keying (RZ-DPSK) systems. An optical frequency discriminator is used to monitor the spectrum broadening caused by timing misalignment. After photo-detection, microwave bandpass filtering and envelope detection, a correct timing is achieved by minimizing the detected microwave power. This proposed method has a large detection dynamic range and is polarization independent. Finally, a novel linearization technique is proposed and demonstrated for cable TV (CATV) external-modulated systems, and it can simultaneously suppress the nonlinear distortions (NLDs) generated in a transmission system and increase the received carrier-to-noise ratio (CNR). This technique is based on offsetting the bias voltage of MZ modulator from its inflection point. Both analytical and experimental results are presented.
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