| his thesis investigates the potential of M-ary ASK, polybinary, polyquaternary, and AM-PSK polybinary signaling schemes operating at 10 Gb/s for increasing the capacity of digital, lightwave communication systems. The premise for exploring these signals was that, because spectral components closer to the carrier experience a lower phase distortion than those components farther away, a dispersion improvement should be offered for signals in which the spectrum is more concentrated about the optical carrier. All signaling methods were investigated through theoretical considerations and computer simulation. The experimental phase of this work focussed on M-ary ASK, where the complete design, construction and testing of a 4-ary ASK lightwave system operating at a bit rate of 10 Gb/s was carried out.;It was found that, of all the polybinary signaling schemes investigated, only the duobinary signal offers an improvement in dispersion immunity, and that no improvement is offered for higher-level polybinary signals because they do not permit the required transmission bandwidth to be further reduced. Hence, it is the spectral occupancy, and not the shape of the power spectrum, that is the important parameter for assessing the dispersion tolerance of polybinary signals. Duobinary signaling allows the dispersion-limited distance to be extended to ;Transmission at 10 Gb/s using 4-ary ASK was experimentally demonstrated over 225 km of standard fiber, and simulations indicate that the dispersion-limited distance can be extended to... |
