Performance Analysis and Signal Characterization for High-Speed Phase-Modulated Lightwave Transmissions
Date Issued
2006
Date
2006
Author(s)
Wang, Hsi-Cheng
DOI
en-US
Abstract
High-speed lightwave transmission techniques, widely deployed in long-haul transmission systems, is currently extending to metro- and access-network for various wideband wireline applications. Differential phase-shift keying (DPSK) and differential quadrature phase-shift keying (DQPSK) signallings have received renewed interest for long-haul transmission or spectrally efficiency systems. Compared with on-off keying (OOK) systems, direct-detection DPSK systems have 3-dB sensitivity improvement and better tolerance to fiber nonlinearity. This dissertation is to provide state-of-art methods in performance analysis and signal characterization for high-speed phase-modulated lightwave transmissions.
Nonlinear phase noise is the main limitation to phase-modulated signals. In addition to intrachannel self-phase modulation (ISPM), in highly dispersive transmission systems with pulse broadening, the interaction of overlapped pulse induces both intrachannel cross-phase modulation (IXPM) and intrachannel four-wave mixing (IFWM). The effects of nonlinear phase noise from both ISPM and IXPM are analyzed and compared with IFWM for return-to-zero differential phase-shift keying (RZ-DPSK) signals. The temporal profile of the standard deviation (STD) of nonlinear phase noise is asymmetrical with its peak. The nonlinear phase noise is found to be the dominant effect to DPSK signals even in highly dispersive systems.
In multiple-channels lightwave transmission systems, without pulse-overlap, RZ-DPSK signals is free from cross-phase modulation (XPM) effect.
However, pulse overlap may cause non-periodic intensity profile that induces non-periodic phase fluctuation to other channels from XPM.
The variance of the differential phase induced by XPM and pulse overlap is derived analytically to show impact of non-periodic intensity profile to RZ-DPSK signals.
The phase jitter of the soliton is analyzed based on first order perturbation theory.
The phase jitter is separated into three independent components induced by amplitude jitter, time and frequency jitter, and the mapping of amplifier noise to phase.
The performance of soliton DPSK signals is derived analytically based on four received signal models: Gaussian, Gaussian linear phase (GLP), independent, and dependent models.
Joint time-frequency representation is able to characterize optical signals affected by fiber- or device-induced impairments.
The complex electric field of phase-modulated signals is retrieved from its time-resolved optical filtering (TROF) measured spectrogram.
An essential component to TROF measurement and algorithm, the complex frequency response of a narrow-band optical filter is measured using microwave network analyzer that has KHz of resolution bandwidth and fraction of dB/degree of accuracy.
With an initial guess from the craters and ridges of the spectrogram, the TROF algorithm based on conjugate gradient method converges rapidly to a mean-square error about 1\% even for signal with chromatic dispersion.
The chromatic dispersion-induced eye-penalty is calculated from the TROF measured electric field for both PSK and DPSK signals.
In contrary to conventional belief, PSK signal has better dispersion tolerance than DPSK signal
The results are also confirmed by computer simulation.
Subjects
差分相位調變
非線性向位雜訊
時頻分析
DPSK
Nonlinear Phase Noise
Time-Frequency Analysis
Type
thesis
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