Recently, Coherent Optical Orthogonal Frequency-division Multiplexing (CO-OFDM) has been considered as a promising technology for high-speed optical transmission due to its easiness of dispersion compensation, high optical spectral efficiency and superior scalability over the channel dispersion and data rate. In this thesis, we conduct analysis on the transceiver nonlinearity impact on a coherent optical Orthogonal Frequency-division Multiplexing (OFDM) system and the feasibility of transmitting up to 1 Tb/s per channel data rate over CO-OFDM WDM systems. / We investigate the optimum design for a CO-OFDM transmitter using an optical In-phase/Quadrature (I/Q) modulator and show by simulation that in contrast to the direct-detected system, the optimal modulator bias point for the coherent system is π, or the null point of the modulator. We also propose and demonstrate through simulation a transmitter side digital signal processing technique including digital clipping and digital pre-distortion to compensate the nonlinearity induced by the OFDM peak-to-average power ratio effect and Mach–Zehnder modulator (MZM). Furthermore, we conduct analysis on the study of nonlinearity and dynamic range for a CO-OFDM receiver induced by the imbalance between the two ports of a balanced receiver. The input power dynamic range and tolerance to the relative-intensity-noise (RIN) are analyzed for the coherent balanced-receiver. / We then explore the transmission performance for high speed wavelength-division multiplexing (WDM) CO-OFDM systems with up to 1Tb/s per channel data rate under the impact of fiber nonlinearity. We find that the optimum fiber launch power increases almost linearly with the increase of data rate. A 7 dB optimum launch power difference is observed between 107-Gb/s and 1.07-Tb/s CO-OFDM systems. We also investigate the dispersion compensation fiber impact and filter concatenation effect issues when upgrading the 10-Gb/s to the future 100-Gb/s CO-OFDM systems. We identify three contributions to the Q degradation for the inline dispersion compensated WDM systems. We show that due to the high spectral efficiency, 100-Gb/s CO-OFDM signals have very high tolerance to the filter narrowing effect, and are resilient to the group ripples from the filter concatenation effect.
| Identifer | oai:union.ndltd.org:ADTP/282411 |
| Date | January 2010 |
| Creators | Tang, Yan |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
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