Fundamental Transmission Limitations on both Ultra-Dense WDM and Subcarrier Multiplexed CATV Systems

Autor: Ming Chia Wu, 吳明佳
Rok vydání: 2004
Druh dokumentu: 學位論文 ; thesis
Popis: 92
This thesis investigates fiber nonlinearity limitation in both ultra dense wavelength division multiplexing (U-DWDM) digital systems and subcarrier multiplexing analog lightwave transmission systems. The main research results are organized into four parts. First of all, transmission performance of ultra-dense 2.5 and 10 Gbps NRZ IM/DD wavelength division multiplexing systems in various single-mode fibers is investigated. Fundamental limiting factors and their remedies by using optimum dispersion compensation for periodically amplified systems in C-band are presented. Second, we found that the combined effects of self- and external-phase modulations must be considered in order to precisely predict the CSO distortions in a long-distance 1550 nm externally-modulated AM-CATV system, especially when the applied phase modulation index and modulating tone frequency to the integrated phase modulator are high. This result has important implications to the optimum design of 1550 nm transmitter for long-distance AM- and QAM-CATV systems. Third, the validity of using multiple CW tones as the signal source to test the linearity of a multichannel M-ary quadrature-amplitude-modulation (M-QAM) subcarrier multiplexed (SCM) lightwave system was investigated. We consider the following representative optical fiber system nonlinearities: (1) laser clipping, and (2) the combined effect of laser frequency chirp and fiber dispersion. The results show that, if all orders of nonlinear distortions (NLDs) in a signal bandwidth are included in the total NLD power, the error caused by replacing M-QAM signals with CW tones can be within measurement uncertainty. Finally, a long-distance 1550 nm subcarrier multiplexed lightwave trunk system which transported 78 channels of 64-QAM signals was demonstrated in a recirculating loop experiment. Each channel can achieve a carrier-to-(noise + nonlinear distortion) ratio of 30 dB after 740 km transmission through conventional single-mode fiber without dispersion compensation.
Databáze: Networked Digital Library of Theses & Dissertations
Externí odkaz: