Taktrückgewinnung aus hochratigen optischen RZ-Datensignalen mittels differentieller optischer Signalverarbeitung

This work describes the set-up, the characteristics and the experimental tests of an optical clock recovery for optical time-division multiplexed (OTDM) signals at a data-rate of 160 Gbit/s. The clock recovery was developed for the use in a receiver of fiber-based optical 160-Gbit/s transmission systems. The clock recovery generates a clock signal that is synchronized to a data stream at the receiver solely with use of the data stream itself. As common receivers cannot process a 160 GHz clock signal, the recovered clock signal is an electrical high frequency signal at a subharmonic frequency of 10 GHz. For this clock recovery a novel phase-comparator with optical differential signal processing was developed and used in a linear phase locked loop (PLL). In this work, the development of this new phase-comparator and its components is described. Its operation characteristics were experimentally analyzed and theoretically specified. An integration in the theory of a linear PLL was performed. The theory provided a description of the operation of the clock recovery during the appearance of a phase-jump as well as a description of the stability and the timing jitter of the recovered clock signal in dependence of the optical input power. The calculations were in good agreement with experimental results, that were obtained when a 40-GHz signal without data modulation was input in the clock recovery. The clock recovery described in this work was successfully applied to several OTDM transmission experiments at a data rate of 160 Gbit/s. The experiments showed that its operation is very insensitive to many signal distortions and provides a high long-term stability. Furthermore it was possible to apply the clock recovery also successfully to a 320 Gbit/s transmission experiment, however with noticeably lower roughness as compared to the roughness at 160 Gbit/s. Likewise the clock recovery was successfully applied to an optical sampling system for 320 Gbit/s. Printed version available from Verlag Dr. Hut: [http://www.dr.hut-verlag.de/