<p> With the increasing demand for data rate and transmission distance, the trend in fiber-optic communications is to build an ultra-high, long-haul transmission system. One of the challenges in this kind of systems comes from the fiber dispersion and dispersion slope. For the wide-band wavelength-division multiplexing (WDM) system or ultra-high bit rate optical time-division multiplexing (OTDM) system, the dispersion slope could be a serious problem to impair the system performance.</p> <p> Many studies have shown that the dispersion and dispersion slope affect the long-haul fiber transmission dramatically, especially for the high-capacity systems. Most of them recommend to totally compensate the dispersion and the dispersion slope simultaneously. And a lot of compensating techniques are proposed. However, it is not easy to realize the simultaneous compensation for the dispersion and dispersion slope in the practical systems. Therefore, the necessity of compensating the dispersion slope in wide-bandwidth systems should be verified.</p> <p> We focus on the study of ultra-high bit rate (160-Gb/s) single-channel fiber-optic transmission. The results show that the dispersion slope is not necessary for the dispersion-managed system when the optimal launch parameters are given. Then we present how to find out the optimum in fiber-optic systems and a novel optimizing technology, space mapping technology (SM) is introduced, which has been successfully applied to the electromagnetic area. An application of SM in optical systems is implemented. By using this smart optimization technique, lots of computational efforts for evaluating the fine model in optimization process are saved.</p> / Thesis / Master of Applied Science (MASc)

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / The necessity of supplying precise time information in large telemetry ground stations and astronomical observatories is very similar. Therefore the way of solving this problem as it is done in the Very Large Telescope of the European Southern Observatory can be easily adopted to telemetry stations and ranges, especially when fiber optics are used. The European Southern Observatory (ESO) is building a new observatory in Chile for the Very Large Telescope (VLT). This VLT consists of 4 telescopes, each of them has a primary mirror diameter of 8 meters. the control architecture is based on workstations and VMEbus computers. The VMEbus computers are distributed over the whole building and are using real time operating system. Since the availability of the Global Positioning System (GPS) the generation of highly accurate timing signals on remote locations without the use of expensive Cesium standards does not create problems any more. However, distribution of a timing signal to many computer with high accuracy is an issue. The accuracy of the commonly used IRIG B-code is not adequate if the requirements are in the 10 microseconds range. This paper presents the design of a timing system that is adopted to the VLT. An overview of the requirements of the Time Reference System (TRS) is given. These requirements have been defined on the basis of experiences with the timing system of the ESO NTT telescope. The hardware units are described. These are a Central Time Standard, a Time Distribution System and a VME Time Interface Module. The distribution is based on fiber optic transmission, using a simple digital modulation that outperforms the analog IRIG B modulation. The Time Interface Module in the computer does not only perform the timing signal decoding but contains also user-programmable timers that are synchronously clocked from the time source. Presently all units of the TRS have been tested and the series production of the distribution and the Time Interface Modules are in progress.